Optimizing Productivity and Resource Use Efficiency Under a Finger Millet-Based Cropping System

Abstract

Finger millet, known for its resilience to adverse climatic conditions, is integrated with various crops to assess the synergistic benefits of intercropping. To obtain intercropping system benefits, crop association, and species combination play a crucial role. Hence, to augment the productivity, profitability, and resource use efficiency under the millet-based system, field research was initiated for three kharif seasons (2021, 2022, and 2023) at the Project Coordinating Unit, University of Agricultural Sciences, Bangalore, Karnataka, India. The outcomes indicated that crops under sole cropping outperformed their intercropping structure in yield. Amongst the intercropping systems, finger millet and groundnut at a 4:2 exhibited a significantly higher finger millet grain equivalent yield (3065 kg/ha), land equivalent ratio (1.64), and area time equivalent ratio (1.38). Also, net returns (Rs. 73,276 ha⁻¹) were realized to be higher in the finger millet + groundnut intercropping system at 4:2 row proportion. Finger millet as a sole crop showed a higher energy output (72,432 MJ ha⁻¹), net energy gain (60,227 MJ ha⁻¹), and energy efficiency (5.95) in relation to other cropping systems. Still, it was analogous to finger millet + groundnut (62,279 MJ ha⁻¹ and 60,378 MJ ha⁻¹, 49,623 MJ ha⁻¹ and 47,628 MJ ha⁻¹, 4.93 and 4.74) at 6:2 and 4:2 row extents, correspondingly). The intercropping of the finger millet with groundnut has demonstrated superior carbon sequestration competencies making them more sustainable and carbon-efficient options compared to sole crops like niger, which showed net carbon loss. The present investigation concluded the adoption of the finger millet + groundnut (4:2) intercropping system as a feasible substitute for attaining overall enhanced productivity with profitability, resource use efficiency, carbon, and energy efficiency.

1. Introduction

Sustainability in rainfed areas is relatively tough to realize due to several limitations like deprived soil productiveness, a lack of irrigation facilities besides moisture stress, trivial holdings, and minimum investment in cultivation. Choosing environmentally efficient crops, such as nutricereals, and embracing intercropping are appropriate choices for productivity maximization. Millets or nutricereals are ancient crops that have a pivotal role in securing the food and nutrition of the nation and promise farming sustainability in rainfed areas [1].

The finger millet area in India is 11.63 lakh ha (1.163 million ha or 11,630 km²) with 1454 kg ha⁻¹ productivity [2]. Majorly, finger millet is cultivated solely in kharif, followed by the sequential crop of oilseeds or pulses. Growing only a crop annually or cereals as a single crop is not highly lucrative at maintaining the state of agriculture to fulfill the varied needs of a hastily expanding population and malnutrition. It is an urgent requirement for the incorporation of pulses or oilseeds in millet production systems to stabilize production to feed the increasing population, besides restoring the soil’s nutritional status. Millets intercropping with pulses or oilseed backs have better scope when using natural resources to an extreme range. The deep tap root system of pulses would be technically more ideal for intercropping with millets, which are shallow-rooted and are consistently rainfed. Intercropping provides numerous advantages pertaining to total crop productivity [3], the effective usage of existing assets, the productivity enhancement of soil, the reduced need for inorganic nutrients [4], runoff water control and erosion, and diversity enhancement [5].

Earlier studies recognized the intercropping benefits related to single cropping under resource limitations [6,7,8], yet region-specific research is essential to inferences on intercropping compared to sole cropping [9]. Since millets are often grown as sole crops and due to climate shifts, especially rainfall uncertainty, it poses severe risks associated with their productivity. Though millet intercropping is being followed in lesser areas, the scientific evaluation for overall system productivity and resource efficiency has not been performed effectively. There is insufficient information on the harmony of different pulses and oilseeds under millet-based associations over semi-arid and arid tracts. Despite increasing interest in sustainable agricultural practices, there is a lack of research on optimizing intercropping systems for millets, especially in semi-arid regions. This gap presents a cognitive need to better understand the synergies between different crops in intercropping systems. Practically, smallholder farmers in these regions often face challenges related to land degradation, water scarcity, and low profitability. Thus, we theorized that millets and pulses/oilseeds are companionable intercropping blends, which would augment the productivity of the whole system. An appropriate mixture at the suitable row ratio would boost the efficiency of land and other resources. So, the field bean, horse gram, groundnut, and niger were grown with finger millet in two drilling designs (4:2 and 6:2), and the performance of individual species combination and drilling forms were related to their corresponding pure form studied in the experiment. The objective was to recognize an appropriate intercrop for advanced crop productivity with higher monetary gains and achieving resource use efficiency besides the outcome of this study, which could emerge as a recommendation to millet farmers, especially for rainfed areas.

2. Material and Methods

2.1. Study Location Description

The field study was executed in the kharif seasons of 2021, 2022, and 2023 (starting in August and ending in December) at the Project Coordinating Unit, University of Agricultural Sciences, Bangalore, (13°4′44.688″ N, 77°34′16.568″ E; elevation 930 m), Karnataka, India.

The experimental site soil was red sandy loam. The soil sample (initial) was collected by an auger (5 cm diameter) from 0 to 30 cm depth of the plough layer in 2021. The outcomes of the composite sample were disclosed as slightly acidic soil with a pH of 5.95, low electrical conductivity of 0.22 dS/m, and organic carbon of 0.36%. In soil, the status of the available nutrients disclosed low nitrogen (249.7 kg/ha), higher phosphorus (71.80 kg/ha), and medium potassium availability (180.40 kg/ha).

2.2. Crop Management

In this field trial, 13 treatments contained 8 intercropping systems finger millet + field bean, finger millet + horse gram, finger millet + groundnut, and finger millet + niger at 2-row proportions (4:2 and 6:2) and five sole cropping sets of field bean, horse gram, groundnut, niger, and finger millet were used. A completely randomized design was adopted, and the treatments were simulated 3 times. Finger millet, horse gram, groundnut, and niger were sown at 30 cm × 10 cm, while 45 cm × 10 cm was adopted in field beans in their individual pure stand. Under the intercropping system, only the component crop of groundnut seeds was dibbled in the specified row proportions (4:2 and 6:2) following the replacement series concept of intercropping.

Farmyard manure, which is well decomposed as suggested for individual crops, was added immediately after the layout, followed by bund formation for each treatment a week before sowing. The manure suggested for individual crops under intercropping treatments was incorporated into the corresponding cropping strip. The required manure quantity for distinct crops in the intercropping system was computed and applied to the percent land possession by the component crop. Recommended nutrients for pulses and oilseed crops were applied at sowing; however, for the finger millet, the 50% nitrogen and complete dosage of phosphorous and other major nutrient potassium as the basal requirement were given, and 50% of the remaining nitrogen was top-dressed at 30 DAS.

2.3. Yield Measurement

Finger millet ear heads and straw in the net plot were reaped distinctly for treatment and separately dried, and ear heads of individual plots were manually threshed, winnowed, and finally cleaned. The yield attained from each treatment area (g/20 m²) was transformed to kg ha⁻¹. Similarly, harvesting was performed for companion crops at the base and permitted to dry (2 days). Harvested crops were tied to bundles and shifted to the farmyard for threshing, wherein the grains were manually separated. In companion crops, the treatment-wise seed yield and the stalk portions were allowed to dry for 6 days, and the weight was documented and articulated in kg ha⁻¹.

2.4. Economic Analysis

The economic efficiency for treatment-wise was computed to know the different intercropping systems’ profitability. To raise crops, inputs, i.e., fuel, manures, seeds, herbicides, fertilizers, plant protection chemicals, labour, etc., were involved in calculating the production cost. The cropping system economic output primary yield (grain or seed) of different companion crops and stalk/stover/straw yield of companion crops was taken into consideration. The input and output existing market prices during the investigation period were regarded for the calculation. Benefit:cost ratio (BC ratio) was calculated as the ratio of gross return to the cost of cultivation [10].

$$\mathrm{G}\mathrm{r}\mathrm{o}\mathrm{s}\mathrm{s} \mathrm{r}\mathrm{e}\mathrm{t}\mathrm{u}\mathrm{r}\mathrm{n}\mathrm{s}\left(\mathrm{I}\mathrm{N}\mathrm{R}/\mathrm{h}\mathrm{a}\right)=\mathrm{G}\mathrm{r}\mathrm{a}\mathrm{i}\mathrm{n}/\mathrm{S}\mathrm{e}\mathrm{e}\mathrm{d} \mathrm{y}\mathrm{i}\mathrm{e}\mathrm{l}\mathrm{d}\left(\mathrm{k}\mathrm{g}/\mathrm{h}\mathrm{a}\right)\times \mathrm{M}\mathrm{a}\mathrm{r}\mathrm{k}\mathrm{e}\mathrm{t} \mathrm{p}\mathrm{r}\mathrm{i}\mathrm{c}\mathrm{e}\left(\mathrm{I}\mathrm{N}\mathrm{R}/\mathrm{h}\mathrm{a}\right)$$

$$\mathrm{N}\mathrm{e}\mathrm{t} \mathrm{r}\mathrm{e}\mathrm{t}\mathrm{u}\mathrm{r}\mathrm{n}\mathrm{s}\left(\mathrm{I}\mathrm{N}\mathrm{R}/\mathrm{h}\mathrm{a}\right)=\mathrm{G}\mathrm{r}\mathrm{o}\mathrm{s}\mathrm{s} \mathrm{r}\mathrm{e}\mathrm{t}\mathrm{u}\mathrm{r}\mathrm{n}\mathrm{s}\left(\mathrm{I}\mathrm{N}\mathrm{R}/\mathrm{h}\mathrm{a}\right)-\mathrm{C}\mathrm{o}\mathrm{s}\mathrm{t} \mathrm{o}\mathrm{f} \mathrm{c}\mathrm{u}\mathrm{l}\mathrm{t}\mathrm{i}\mathrm{v}\mathrm{a}\mathrm{t}\mathrm{i}\mathrm{o}\mathrm{n} (\mathrm{I}\mathrm{N}\mathrm{R}/\mathrm{h}\mathrm{a})$$

$$\mathrm{B}\mathrm{e}\mathrm{n}\mathrm{e}\mathrm{f}\mathrm{i}\mathrm{t}-\mathrm{c}\mathrm{o}\mathrm{s}\mathrm{t} \mathrm{r}\mathrm{a}\mathrm{t}\mathrm{i}\mathrm{o}={\displaystyle \frac{\mathrm{G}\mathrm{r}\mathrm{o}\mathrm{s}\mathrm{s} \mathrm{r}\mathrm{e}\mathrm{t}\mathrm{u}\mathrm{r}\mathrm{n}\mathrm{s} (\mathrm{I}\mathrm{N}\mathrm{R}/\mathrm{h}\mathrm{a})}{\mathrm{C}\mathrm{o}\mathrm{s}\mathrm{t} \mathrm{o}\mathrm{f} \mathrm{c}\mathrm{u}\mathrm{l}\mathrm{t}\mathrm{i}\mathrm{v}\mathrm{a}\mathrm{t}\mathrm{i}\mathrm{o}\mathrm{n} (\mathrm{I}\mathrm{N}\mathrm{R}/\mathrm{h}\mathrm{a})}}$$

The exchange rates at the study time were as follows:

• 1 USD ≈ 82.57 INR;
• 1 EURO ≈ 89.29 INR;
• 1 CNY ≈ 11.65 INR.

2.5. Intercropping Indices

2.5.1. Main Crop Grain Equivalent Yield

This designates the overall system productivity or output of the cropping arrangement. Here, crop yields were transformed into the main crop grain yield equivalent (MGEY) pertaining to the price existing at the market using the formula given by [11].

$$\mathrm{M}\mathrm{G}\mathrm{E}\mathrm{Y} (\mathrm{k}\mathrm{g}/\mathrm{h}\mathrm{a})=\mathrm{F}\mathrm{i}\mathrm{n}\mathrm{g}\mathrm{e}\mathrm{r} \mathrm{m}\mathrm{i}\mathrm{l}\mathrm{l}\mathrm{e}\mathrm{t} \mathrm{y}\mathrm{i}\mathrm{e}\mathrm{l}\mathrm{d} (\mathrm{k}\mathrm{g}/\mathrm{h}\mathrm{a})+{\displaystyle \frac{\mathrm{I}\mathrm{n}\mathrm{t}\mathrm{e}\mathrm{r}\mathrm{c}\mathrm{r}\mathrm{o}\mathrm{p} \mathrm{y}\mathrm{i}\mathrm{e}\mathrm{l}\mathrm{d} (\mathrm{k}\mathrm{g}/\mathrm{h}\mathrm{a})\times \mathrm{I}\mathrm{n}\mathrm{t}\mathrm{e}\mathrm{r}\mathrm{c}\mathrm{r}\mathrm{o}\mathrm{p} \mathrm{p}\mathrm{r}\mathrm{i}\mathrm{c}\mathrm{e} (\mathrm{I}\mathrm{N}\mathrm{R}/\mathrm{k}\mathrm{g})}{\mathrm{F}\mathrm{i}\mathrm{n}\mathrm{g}\mathrm{e}\mathrm{r} \mathrm{m}\mathrm{i}\mathrm{l}\mathrm{l}\mathrm{e}\mathrm{t} \mathrm{p}\mathrm{r}\mathrm{i}\mathrm{c}\mathrm{e} (\mathrm{I}\mathrm{N}\mathrm{R}/\mathrm{k}\mathrm{g})}}$$

2.5.2. Land Equivalent Ratio (LER)

LER gives details on the relative sole crop land area that is needed to produce the yield attained under intercropping. It was calculated in line with the method, as suggested by [12].

$$\mathrm{L}\mathrm{E}\mathrm{R}={\displaystyle \frac{\mathrm{Y}\mathrm{i}\mathrm{e}\mathrm{l}\mathrm{d} \mathrm{o}\mathrm{f} \mathrm{F}\mathrm{M} \mathrm{i}\mathrm{n} \mathrm{i}\mathrm{n}\mathrm{t}\mathrm{e}\mathrm{r}\mathrm{c}\mathrm{r}\mathrm{o}\mathrm{p}\mathrm{p}\mathrm{i}\mathrm{n}\mathrm{g}}{\mathrm{P}\mathrm{u}\mathrm{r}\mathrm{e} \mathrm{c}\mathrm{r}\mathrm{o}\mathrm{p} \mathrm{y}\mathrm{i}\mathrm{e}\mathrm{l}\mathrm{d} \mathrm{o}\mathrm{f} \mathrm{F}\mathrm{M}}}+{\displaystyle \frac{\mathrm{Y}\mathrm{i}\mathrm{e}\mathrm{l}\mathrm{d} \mathrm{o}\mathrm{f} \mathrm{c}\mathrm{o}\mathrm{m}\mathrm{p}\mathrm{a}\mathrm{n}\mathrm{i}\mathrm{o}\mathrm{n} \mathrm{s}\mathrm{p}\mathrm{p} \mathrm{i}\mathrm{n} \mathrm{i}\mathrm{n}\mathrm{t}\mathrm{e}\mathrm{r}\mathrm{c}\mathrm{r}\mathrm{o}\mathrm{p}\mathrm{p}\mathrm{i}\mathrm{n}\mathrm{g}}{\mathrm{P}\mathrm{u}\mathrm{r}\mathrm{e} \mathrm{c}\mathrm{r}\mathrm{o}\mathrm{p} \mathrm{y}\mathrm{i}\mathrm{e}\mathrm{l}\mathrm{d} \mathrm{o}\mathrm{f} \mathrm{c}\mathrm{o}\mathrm{m}\mathrm{p}\mathrm{a}\mathrm{n}\mathrm{i}\mathrm{o}\mathrm{n} \mathrm{s}\mathrm{p}\mathrm{p}}}$$

2.5.3. Area Time Equivalent Ratio (ATER)

ATER offers an accurate assessment of the extra time taken by the component crops under intercropping to harvest an equal quantum of yield under monoculture. It was calibrated using a formula suggested by [13].

$$\mathrm{A}\mathrm{T}\mathrm{E}\mathrm{R}=\left[{\displaystyle \frac{\mathrm{I}\mathrm{n}\mathrm{t}\mathrm{e}\mathrm{r}\mathrm{c}\mathrm{r}\mathrm{o}\mathrm{p} \mathrm{y}\mathrm{i}\mathrm{e}\mathrm{l}\mathrm{d} \mathrm{o}\mathrm{f} \mathrm{F}\mathrm{M}}{\mathrm{P}\mathrm{u}\mathrm{r}\mathrm{e} \mathrm{c}\mathrm{r}\mathrm{o}\mathrm{p} \mathrm{y}\mathrm{i}\mathrm{e}\mathrm{l}\mathrm{d} \mathrm{o}\mathrm{f} \mathrm{F}\mathrm{M}}}\times \mathrm{t}\mathrm{a}\right]+\left[{\displaystyle \frac{\mathrm{I}\mathrm{n}\mathrm{t}\mathrm{e}\mathrm{r}\mathrm{c}\mathrm{r}\mathrm{o}\mathrm{p} \mathrm{y}\mathrm{i}\mathrm{e}\mathrm{l}\mathrm{d} \mathrm{o}\mathrm{f} \mathrm{c}\mathrm{o}\mathrm{m}\mathrm{p}\mathrm{a}\mathrm{n}\mathrm{i}\mathrm{o}\mathrm{n} \mathrm{s}\mathrm{p}\mathrm{p}}{\mathrm{P}\mathrm{u}\mathrm{r}\mathrm{e} \mathrm{c}\mathrm{r}\mathrm{o}\mathrm{p} \mathrm{y}\mathrm{i}\mathrm{e}\mathrm{l}\mathrm{d} \mathrm{o}\mathrm{f} \mathrm{c}\mathrm{o}\mathrm{m}\mathrm{p}\mathrm{a}\mathrm{n}\mathrm{i}\mathrm{o}\mathrm{n} \mathrm{s}\mathrm{p}\mathrm{p}}}\times \mathrm{t}\mathrm{b}\right]$$

‘ta’ and ‘tb’ represent the duration (days) of finger millet and companion crops, respectively. T is the intercropping system’s whole duration (days).

2.5.4. Production Use Efficiency (PUE)

The details of the perday productivity of the system in production use efficiency was calculated by making use of the formula given below.

$$\mathrm{P}\mathrm{U}\mathrm{E}={\displaystyle \frac{\mathrm{Y}\mathrm{i}\mathrm{e}\mathrm{l}\mathrm{d} \mathrm{o}\mathrm{f} \mathrm{F}\mathrm{M} (\mathrm{k}\mathrm{g}/\mathrm{h}\mathrm{a})+\mathrm{Y}\mathrm{i}\mathrm{e}\mathrm{l}\mathrm{d} \mathrm{o}\mathrm{f} \mathrm{c}\mathrm{o}\mathrm{m}\mathrm{p}\mathrm{a}\mathrm{n}\mathrm{i}\mathrm{o}\mathrm{n} \mathrm{s}\mathrm{p}\mathrm{p} (\mathrm{k}\mathrm{g}/\mathrm{h}\mathrm{a})}{\mathrm{D}\mathrm{u}\mathrm{r}\mathrm{a}\mathrm{t}\mathrm{i}\mathrm{o}\mathrm{n} \mathrm{o}\mathrm{f} \mathrm{F}\mathrm{M}\left(\mathrm{d}\mathrm{a}\mathrm{y}\mathrm{s}\right)+\mathrm{D}\mathrm{u}\mathrm{r}\mathrm{a}\mathrm{t}\mathrm{i}\mathrm{o}\mathrm{n} \mathrm{o}\mathrm{f} \mathrm{c}\mathrm{o}\mathrm{m}\mathrm{p}\mathrm{a}\mathrm{n}\mathrm{i}\mathrm{o}\mathrm{n} \mathrm{s}\mathrm{p}\mathrm{p} \left(\mathrm{d}\mathrm{a}\mathrm{y}\mathrm{s}\right)}}$$

2.5.5. Land Utilization Efficiency (LUE)

LUE was computed using the formula given by [14].

$$\mathrm{L}\mathrm{U}\mathrm{E} (\mathrm{\%})={\displaystyle \frac{\mathrm{L}\mathrm{E}\mathrm{R}+\mathrm{A}\mathrm{T}\mathrm{E}\mathrm{R}}{2}}\times 100$$

2.5.6. Relative Value Total (RVT)

RVT denotes the intercropping system’s relative value compared to the two monocultures and was calculated by the following equation as suggested by [15]. The intercropping system is advantageous if RVT is greater than 1.

$$\mathrm{R}\mathrm{V}\mathrm{T}={\displaystyle \frac{\left(\mathrm{P}\mathrm{r}\mathrm{i}\mathrm{c}\mathrm{e} \mathrm{o}\mathrm{f} \mathrm{F}\mathrm{M}\times \mathrm{Y}\mathrm{i}\mathrm{e}\mathrm{l}\mathrm{d} \mathrm{o}\mathrm{f} \mathrm{F}\mathrm{M} \mathrm{i}\mathrm{n} \mathrm{i}\mathrm{n}\mathrm{t}\mathrm{e}\mathrm{r}\mathrm{c}\mathrm{r}\mathrm{o}\mathrm{p}\mathrm{p}\mathrm{i}\mathrm{n}\mathrm{g}\right)+(\mathrm{P}\mathrm{r}\mathrm{i}\mathrm{c}\mathrm{e} \mathrm{o}\mathrm{f} \mathrm{c}\mathrm{o}\mathrm{m}\mathrm{p}\mathrm{a}\mathrm{n}\mathrm{i}\mathrm{o}\mathrm{n} \mathrm{s}\mathrm{p}\mathrm{p}\times \mathrm{Y}\mathrm{i}\mathrm{e}\mathrm{l}\mathrm{d} \mathrm{o}\mathrm{f} \mathrm{c}\mathrm{o}\mathrm{m}\mathrm{p}\mathrm{a}\mathrm{n}\mathrm{i}\mathrm{o} \mathrm{n}\mathrm{s}\mathrm{p}\mathrm{p})}{(\mathrm{P}\mathrm{r}\mathrm{i}\mathrm{c}\mathrm{e} \mathrm{o}\mathrm{f} \mathrm{F}\mathrm{M}\times \mathrm{Y}\mathrm{i}\mathrm{e}\mathrm{l}\mathrm{d} \mathrm{o}\mathrm{f} \mathrm{F}\mathrm{M} \mathrm{i}\mathrm{n} \mathrm{m}\mathrm{o}\mathrm{n}\mathrm{o}\mathrm{c}\mathrm{u}\mathrm{l}\mathrm{t}\mathrm{u}\mathrm{r}\mathrm{e})}}$$

2.6. Energy Analysis

Under different cropping systems, to calculate the energetics, a comprehensive account of inputs and outputs of all crops was prepared, which is inclusive of land preparation, fertilizer, seed, weed, labour, management, fuel, machinery power, seed/grain yields, and stalk/straw/stover yield. The input and output physical units were converted into energy units with the help of energy coefficients. The inputs used in the system and energy input for the individual operation used were totalled to determine the overall input of energy. The numerous energy equivalents were computed via the methodology suggested by [16].

$$\mathrm{E}\mathrm{n}\mathrm{e}\mathrm{r}\mathrm{g}\mathrm{y} \mathrm{u}\mathrm{s}\mathrm{e} \mathrm{e}\mathrm{f}\mathrm{f}\mathrm{i}\mathrm{c}\mathrm{i}\mathrm{e}\mathrm{n}\mathrm{c}\mathrm{y}={\displaystyle \frac{\mathrm{E}\mathrm{n}\mathrm{e}\mathrm{r}\mathrm{g}\mathrm{y} \mathrm{o}\mathrm{u}\mathrm{t}\mathrm{p}\mathrm{u}\mathrm{t} \left(\mathrm{M}\mathrm{J}\right)}{\mathrm{E}\mathrm{n}\mathrm{e}\mathrm{r}\mathrm{g}\mathrm{y} \mathrm{i}\mathrm{n}\mathrm{p}\mathrm{u}\mathrm{t} \left(\mathrm{M}\mathrm{J}\right)}}$$

$$\mathrm{N}\mathrm{e}\mathrm{t} \mathrm{e}\mathrm{n}\mathrm{e}\mathrm{r}\mathrm{g}\mathrm{y}=\mathrm{T}\mathrm{o}\mathrm{t}\mathrm{a}\mathrm{l} \mathrm{e}\mathrm{n}\mathrm{e}\mathrm{r}\mathrm{g}\mathrm{y} \mathrm{o}\mathrm{u}\mathrm{t}\mathrm{p}\mathrm{u}\mathrm{t}\left(\mathrm{M}\mathrm{J}\right)-\mathrm{T}\mathrm{o}\mathrm{t}\mathrm{a}\mathrm{l} \mathrm{e}\mathrm{n}\mathrm{e}\mathrm{r}\mathrm{g}\mathrm{y} \mathrm{i}\mathrm{n}\mathrm{p}\mathrm{u}\mathrm{t} \left(\mathrm{M}\mathrm{J}\right)$$

$$\mathrm{E}\mathrm{n}\mathrm{e}\mathrm{r}\mathrm{g}\mathrm{y} \mathrm{p}\mathrm{r}\mathrm{o}\mathrm{f}\mathrm{i}\mathrm{t}\mathrm{a}\mathrm{b}\mathrm{i}\mathrm{l}\mathrm{i}\mathrm{t}\mathrm{y}={\displaystyle \frac{\mathrm{N}\mathrm{e}\mathrm{t} \mathrm{e}\mathrm{n}\mathrm{e}\mathrm{r}\mathrm{g}\mathrm{y} \mathrm{g}\mathrm{a}\mathrm{i}\mathrm{n} \left(\mathrm{M}\mathrm{J}\right)}{\mathrm{T}\mathrm{o}\mathrm{t}\mathrm{a}\mathrm{l} \mathrm{e}\mathrm{n}\mathrm{e}\mathrm{r}\mathrm{g}\mathrm{y} \mathrm{i}\mathrm{n}\mathrm{p}\mathrm{u}\mathrm{t} (\mathrm{M}\mathrm{J}/\mathrm{h}\mathrm{a})}}$$

$$\mathrm{D}\mathrm{i}\mathrm{r}\mathrm{e}\mathrm{c}\mathrm{t} \mathrm{e}\mathrm{n}\mathrm{e}\mathrm{r}\mathrm{g}\mathrm{y}=\mathrm{L}\mathrm{a}\mathrm{b}\mathrm{o}\mathrm{u}\mathrm{r}+\mathrm{F}\mathrm{u}\mathrm{e}\mathrm{l}$$

$$\mathrm{I}\mathrm{n}\mathrm{d}\mathrm{i}\mathrm{r}\mathrm{e}\mathrm{c}\mathrm{t} \mathrm{e}\mathrm{n}\mathrm{e}\mathrm{r}\mathrm{g}\mathrm{y}=\mathrm{S}\mathrm{e}\mathrm{e}\mathrm{d}\mathrm{s}+\mathrm{F}\mathrm{e}\mathrm{r}\mathrm{t}\mathrm{i}\mathrm{l}\mathrm{i}\mathrm{z}\mathrm{e}\mathrm{r}\mathrm{s}+\mathrm{C}\mathrm{h}\mathrm{e}\mathrm{m}\mathrm{i}\mathrm{c}\mathrm{a}\mathrm{l}\mathrm{s}+\mathrm{M}\mathrm{a}\mathrm{c}\mathrm{h}\mathrm{i}\mathrm{n}\mathrm{e}\mathrm{r}\mathrm{i}\mathrm{e}\mathrm{s}$$

$$\mathrm{R}\mathrm{e}\mathrm{n}\mathrm{e}\mathrm{w}\mathrm{a}\mathrm{b}\mathrm{l}\mathrm{e} \mathrm{e}\mathrm{n}\mathrm{e}\mathrm{r}\mathrm{g}\mathrm{y}=\mathrm{L}\mathrm{a}\mathrm{b}\mathrm{o}\mathrm{u}\mathrm{r}+\mathrm{O}\mathrm{r}\mathrm{g}\mathrm{a}\mathrm{n}\mathrm{i}\mathrm{c} \mathrm{M}\mathrm{a}\mathrm{n}\mathrm{u}\mathrm{r}\mathrm{e}$$

$$\mathrm{N}\mathrm{o}\mathrm{n}-\mathrm{r}\mathrm{e}\mathrm{n}\mathrm{e}\mathrm{w}\mathrm{a}\mathrm{b}\mathrm{l}\mathrm{e} \mathrm{e}\mathrm{n}\mathrm{e}\mathrm{r}\mathrm{g}\mathrm{y}=\mathrm{F}\mathrm{u}\mathrm{e}\mathrm{l}+\mathrm{E}\mathrm{l}\mathrm{e}\mathrm{c}\mathrm{t}\mathrm{r}\mathrm{i}\mathrm{c}\mathrm{i}\mathrm{t}\mathrm{y}+\mathrm{S}\mathrm{e}\mathrm{e}\mathrm{d}+\mathrm{F}\mathrm{e}\mathrm{r}\mathrm{t}\mathrm{i}\mathrm{l}\mathrm{i}\mathrm{z}\mathrm{e}\mathrm{r}\mathrm{s}+\mathrm{C}\mathrm{h}\mathrm{e}\mathrm{m}\mathrm{i}\mathrm{c}\mathrm{a}\mathrm{l}\mathrm{s}+\mathrm{M}\mathrm{a}\mathrm{c}\mathrm{h}\mathrm{i}\mathrm{n}\mathrm{e}\mathrm{r}\mathrm{i}\mathrm{e}\mathrm{s}$$

The energy coefficients for the inputs used are given in the parenthesis under each input as follows: 50 HP tractor (64.8 MJ/h), plough (62.70 MJ/h), diesel (56.31 MJ/l), male labour (1.96 MJ/h), female labour (1.57 MJ/h), FYM (0.47 MJ/kg), nitrogen (60.60 MJ/kg), phosphorus (11.1 MJ/kg), potassium (6.70 MJ/kg), and harvesting labour (1.57 MJ/h) according to [17]. Furthermore, seed (20.4 MJ/kg), pendimethalin (150.9 MJ/kg), and thresher (68.4 MJ/h) were used, as reported by [18,19,20], respectively. Similarly, the energy coefficients for outputs, i.e., seed (14.7 MJ/kg) and straw (12.5 MJ/kg), were used as provided by [21].

2.7. Carbon Footprint

To determine the possible greenhouse emissions of various cropping systems, the carbon footprint of each system was examined. The amount of carbon dioxide freed from several sources of input, including manure, fertilizer, herbicide, and fuel, was calculated and expressed as kg CO₂-eq per ha. By adding up individual crops, CO₂ emissions in the system, according to the area those crops occupied, and the cropping system’s overall CO₂ emissions were calculated. Spatial carbon footprint is the area basis equivalent (kg CO₂-eq ha⁻¹). The total value of carbon dioxide liberated in each cropping system under individual input was divided by 3.66, as per the approach proposed by [22] to obtain equivalent carbon (kg CE ha⁻¹) from spatial C footprint (kg CO₂-eq ha⁻¹). We evaluated the carbon dynamics of each cropping system for carbon gain, carbon output, and efficiency of carbon via the methodology of [23].

$$\mathrm{C}\mathrm{a}\mathrm{r}\mathrm{b}\mathrm{o}\mathrm{n} \mathrm{f}\mathrm{o}\mathrm{o}\mathrm{t}\mathrm{p}\mathrm{r}\mathrm{i}\mathrm{n}\mathrm{t}={\displaystyle \frac{\mathrm{C}\mathrm{a}\mathrm{r}\mathrm{b}\mathrm{o}\mathrm{n} \mathrm{e}\mathrm{m}\mathrm{i}\mathrm{s}\mathrm{s}\mathrm{i}\mathrm{o}\mathrm{n} (\mathrm{k}\mathrm{g} \mathrm{C}\mathrm{E} \mathrm{k}\mathrm{g}/\mathrm{h}\mathrm{a})}{\mathrm{F}\mathrm{i}\mathrm{n}\mathrm{g}\mathrm{e}\mathrm{r} \mathrm{m}\mathrm{i}\mathrm{l}\mathrm{l}\mathrm{e}\mathrm{t} \mathrm{e}\mathrm{q}\mathrm{u}\mathrm{i}\mathrm{v}\mathrm{a}\mathrm{l}\mathrm{e}\mathrm{n}\mathrm{t} \mathrm{y}\mathrm{i}\mathrm{e}\mathrm{l}\mathrm{d} (\mathrm{k}\mathrm{g}/\mathrm{h}\mathrm{a})}}$$

$$\mathrm{C}\mathrm{a}\mathrm{r}\mathrm{b}\mathrm{o}\mathrm{n} \mathrm{o}\mathrm{u}\mathrm{t}\mathrm{p}\mathrm{u}\mathrm{t} (\mathrm{k}\mathrm{g} \mathrm{C}\mathrm{E}/\mathrm{h}\mathrm{a})=\mathrm{T}\mathrm{o}\mathrm{t}\mathrm{a}\mathrm{l} \mathrm{b}\mathrm{i}\mathrm{o}\mathrm{m}\mathrm{a}\mathrm{s}\mathrm{s}\times 0.44$$

$$\mathrm{N}\mathrm{e}\mathrm{t} \mathrm{c}\mathrm{a}\mathrm{r}\mathrm{b}\mathrm{o}\mathrm{n} \mathrm{g}\mathrm{a}\mathrm{i}\mathrm{n}=\mathrm{C}\mathrm{a}\mathrm{r}\mathrm{b}\mathrm{o}\mathrm{n} \mathrm{o}\mathrm{u}\mathrm{t}\mathrm{p}\mathrm{u}\mathrm{t} (\mathrm{k}\mathrm{g} \mathrm{C}\mathrm{E}/\mathrm{h}\mathrm{a})-\mathrm{C}\mathrm{a}\mathrm{r}\mathrm{b}\mathrm{o}\mathrm{n} \mathrm{i}\mathrm{n}\mathrm{p}\mathrm{u}\mathrm{t} (\mathrm{k}\mathrm{g} \mathrm{C}\mathrm{E}/\mathrm{h}\mathrm{a})$$

$$\mathrm{C}\mathrm{a}\mathrm{r}\mathrm{b}\mathrm{o}\mathrm{n} \mathrm{e}\mathrm{f}\mathrm{f}\mathrm{i}\mathrm{c}\mathrm{i}\mathrm{e}\mathrm{n}\mathrm{c}\mathrm{y} \mathrm{r}\mathrm{a}\mathrm{t}\mathrm{i}\mathrm{o}={\displaystyle \frac{\mathrm{C}\mathrm{a}\mathrm{r}\mathrm{b}\mathrm{o}\mathrm{n} \mathrm{o}\mathrm{u}\mathrm{t}\mathrm{p}\mathrm{u}\mathrm{t} (\mathrm{k}\mathrm{g} \mathrm{C}\mathrm{E}/\mathrm{h}\mathrm{a})}{\mathrm{C}\mathrm{a}\mathrm{r}\mathrm{b}\mathrm{o}\mathrm{n} \mathrm{i}\mathrm{n}\mathrm{p}\mathrm{u}\mathrm{t} (\mathrm{k}\mathrm{g} \mathrm{C}\mathrm{E}/\mathrm{h}\mathrm{a})}}$$

$$\mathrm{C}\mathrm{a}\mathrm{r}\mathrm{b}\mathrm{o}\mathrm{n} \mathrm{e}\mathrm{f}\mathrm{f}\mathrm{i}\mathrm{c}\mathrm{i}\mathrm{e}\mathrm{n}\mathrm{c}\mathrm{y} (\mathrm{k}\mathrm{g}/\mathrm{k}\mathrm{g} \mathrm{C}\mathrm{E})={\displaystyle \frac{\mathrm{F}\mathrm{i}\mathrm{n}\mathrm{g}\mathrm{e}\mathrm{r}\mathrm{m}\mathrm{i}\mathrm{l}\mathrm{l}\mathrm{e}\mathrm{t} \mathrm{e}\mathrm{q}\mathrm{u}\mathrm{i}\mathrm{v}\mathrm{a}\mathrm{l}\mathrm{e}\mathrm{n}\mathrm{t} \mathrm{y}\mathrm{i}\mathrm{e}\mathrm{l}\mathrm{d} (\mathrm{k}\mathrm{g}/\mathrm{h}\mathrm{a})}{\mathrm{C}\mathrm{a}\mathrm{r}\mathrm{b}\mathrm{o}\mathrm{n} \mathrm{i}\mathrm{n}\mathrm{p}\mathrm{u}\mathrm{t} (\mathrm{k}\mathrm{g} \mathrm{C}\mathrm{E}/\mathrm{h}\mathrm{a})}}$$

The carbon equivalents for various agricultural inputs used in the experiment are as follows: Plough—31.97 CO₂-eq/h and furrow opener—24.9 CO₂-eq/h [24]; tooth cultivator (4.00 CO₂-eq/h), rotavator (2.00 CO₂-eq/h), nitrogen (4.96 CO₂-eq/kg), phosphorus (1.35 CO₂-eq/kg), potassium (0.58 CO₂-eq/kg), pendimethalin (6.30 CO₂-eq /kg) as given by [22]; diesel (3.32 CO₂-eq/L) and labour (0.86 CO₂-eq /h) as given by [25]; FYM—0.07 CO₂-eq /kg [26], and seed—1.22 CO₂-eq/kg [27].

2.8. Statistical Study

The documented data on different traits were applied to Fisher’s technique of variance study, and data interpretation was made, as given in the F-test, p = 0.05. Whenever amid the treatments, the significant F-test was found for comparison, and the critical differences (CD) value would be figured out. If not, ‘NS’ (non-significant) is shown, divergent from the CD values abbreviation. To quantify the impact of each explanatory variable, linear regression analysis was used on positively and strongly associated variables.

3. Results

3.1. Base and Companion Crop Yield

Grouped data on three years of finger millet grain production is shown in

Table 1. Grain yield of main crop, inter-crop and the finger millet equivalent yield of finger millet-based cropping system (grouped data of three years).

Treatments	Grain Yield of Main Crop (kg/ha)	Straw Yield of Main Crop (kg/ha)	Main Crop Harvest Index (%)	Grain Yield of Inter-Crop (kg/ha)	MGEY (kg/ha)
T1: Finger millet + Field bean (4:2)	1659	2666	38.57	241	2025
T2: Finger millet + Field bean (6:2)	1417	2510	36.04	167	1671
T3: Finger millet + Horse gram (4:2)	1964	3106	38.77	234	2230
T4: Finger millet + Horse gram (6:2)	1610	2894	38.90	184	1820
T5: Finger millet + Groundnut (4:2)	2292	3537	38.89	630	3065
T6: Finger millet + Groundnut (6:2)	2166	3073	38.87	456	2727
T7: Finger millet + Niger (4:2)	1486	2441	37.75	104	1680
T8: Finger millet + Niger (6:2)	1806	2917	38.25	79	1955
T9: Sole crop of Finger millet	2312	3726	38.44	-	2290
T10: Sole crop of Field bean	-	-	-	587	893
T11: Sole crop of Horse gram	-	-	-	425	484
T12: Sole crop of Groundnut	-	-	-	999	1228
T13: Sole crop of Niger	-	-	-	278	523
S. Em.±	64.46	116.25	0.9	17.4	62.84
C.D. (5%)	193.26	384.51	2.69	51.03	183.41

. Sole cropping (finger millet) exhibited a pointedly higher grain yield (2312 kg ha⁻¹) in contrast to intercropping. The row proportion significantly affected the finger millet yield. The grain yield was found to be significantly higher with the 4:2 ratio with field bean (17.08%), horsegram (21.98%), and groundnut (5.82%) than the 6:2 ratio, except niger. The significantly higher base crop yield (finger millet) was seen when it was inter-seeded with groundnut in a 4:2 row ratio (2292 kg ha⁻¹) and found statistically on par with finger millet + groundnut at a 6:2 row ratio (2166 kg ha⁻¹). Similarly, the inter-crops were significant in yield performance under sole cropping related to intercropping, wherein the groundnut sole cropping grain yield was the highest (999 kg ha⁻¹).

3.2. Main Crop Grain Equivalent Yield (MGEY)

Significant improvement in MGEY was observed in intercropping compared to sole cropping. Finger millet + groundnut in a 4:2 row ratio showed significantly higher MGEY (3065 kg ha⁻¹), followed by finger millet + groundnut in a 6:2 row ratio (2727 kg ha⁻¹).

3.3. Yield Attributes of Main and Companion Crop

The three years of grouped data on yield parameters of the main crop and companion crop are shown in

Table 2. Yield attributes of the main crop in the finger millet-based cropping system (grouped data of three years).

Treatments	Number of Productive Tillers/Hills in Base Crop	Number of Earheads/Hill	Number of Grains/Earhead	1000 Seed Weight (g)
T1: Finger millet + Field bean (4:2)	3.70	11.61	1767	2.90
T2: Finger millet + Field bean (6:2)	2.62	8.81	1679	2.97
T3: Finger millet + Horse gram (4:2)	3.85	12.47	1833	2.91
T4: Finger millet + Horse gram (6:2)	3.66	11.13	1732	2.90
T5: Finger millet + Groundnut (4:2)	4.19	13.83	1873	3.08
T6: Finger millet + Groundnut (6:2)	4.14	13.43	1911	3.07
T7: Finger millet + Niger (4:2)	3.42	10.46	1715	3.08
T8: Finger millet + Niger (6:2)	3.81	11.96	1798	3.26
T9: Sole crop of Finger millet	4.20	14.00	1984	3.00
T10: Sole crop of Field bean	-	-	-	-
T11: Sole crop of Horse gram	-	-	-	-
T12: Sole crop of Groundnut	-	-	-	-
T13: Sole crop of Niger	-	-	-	-
S. Em.±	0.13	0.4	59.12	0.10
C.D. (5%)	0.38	1.21	177.25	0.30

and

Table 3. The yield attributes of companion crops in the finger millet-based cropping system (grouped data of three years).

Treatments	Number of Branches/Plants	Number of Pods/Plant or Capitula/Plant	Number of Seeds/Pod or Seeds/Capitula
T1: Finger millet + Field bean (4:2)	6.62	61.45	4.00
T2: Finger millet + Field bean (6:2)	6.89	64.48	4.33
T3: Finger millet + Horse gram (4:2)	2.99	38.34	4.33
T4: Finger millet + Horse gram (6:2)	2.99	40.94	4.45
T5: Finger millet + Groundnut (4:2)	-	30.33	2.98
T6: Finger millet + Groundnut (6:2)	-	31.51	2.98
T7: Finger millet + Niger (4:2)	10.43	76.57	11.05
T8: Finger millet + Niger (6:2)	10.59	79.21	11.56
T9: Sole crop of Finger millet	-	-	-
T10: Sole crop of Field bean	7.83	72.15	4.74
T11: Sole crop of Horse gram	3.31	45.21	4.60
T12: Sole crop of Groundnut	-	34.16	3.38
T13: Sole crop of Niger	11.34	84.28	12.08
S. Em.±	0.31	2.20	0.27
C.D. (5%)	0.92	6.45	0.81

. The yield attributes of the base crop varied significantly owing to the cropping system. The base crop showed significantly higher productive tillers/hill (4.20), earheads/hill (14.00), and grains/earhead (1984) and among intercropping associations, finger millet + groundnut at a 4:2 row ratio showed a significantly higher number of productive tillers/hill (4.19), earheads/hill (13.83) and grains/earhead (1873) and was on par to finger millet + groundnut (6:2) and finger millet + horse gram (4:2). On the other hand, the lowest values obtained in the yield parameters were noticed in the finger millet + filed bean (6:2). However, the test weight of the finger millet was observed to be non-significant with reference to row proportions and different crop associations. The sole cropping of companion crops again showed a significantly higher number of branches in niger (11.34), field bean (7.83), and horse gram (3.31). Similarly, pod numbers/plants and seed numbers/pods were also found to have higher values with the sole cropping of the companion crop.

3.4. Economics

The returns and cost evaluation were worked out by taking the experimental period variable costs, and the outcomes are provided (

Table 4. The economics of the finger millet-based intercropping system (grouped data of three years).

Treatments	Gross Returns (Rs. ha−1)	Net Returns (Rs. ha−1)	BC Ratio
T1: Finger millet + Field bean (4:2)	77,476	41,214	2.15
T2: Finger millet + Field bean (6:2)	63,997	27,964	1.80
T3: Finger millet + Horse gram (4:2)	85,319	50,571	2.46
T4: Finger millet + Horse gram (6:2)	69,625	35,038	2.02
T5: Finger millet + Groundnut (4:2)	116,782	73,276	2.68
T6: Finger millet + Groundnut (6:2)	104,015	61,857	2.47
T7: Finger millet + Niger (4:2)	64,495	30,595	1.91
T8: Finger millet + Niger (6:2)	74,958	41,723	2.27
T9: Sole crop of Finger millet	87,790	56,844	2.97
T10: Sole crop of Field bean	33,609	2894	1.14
T11: Sole crop of Horse gram	18,060	−4032	0.88
T12: Sole crop of Groundnut	47,593	−1387	0.97
T13: Sole crop of Niger	26,716	5635	1.57

). Finger millet intercropping with groundnut at a 4:2 row proportion has registered the maximum gross returns (INR 116,782 ha⁻¹), net returns (INR 73,276 ha⁻¹) and benefit-cost proportion (2.68) while under sole cropping’ the finger millet fetched higher returns of gross (INR 87,790 ha⁻¹), net returns (INR 56,844 ha⁻¹) and the BC ratio (2.97). Furthermore, it showed that the finger millet intercropped with all companion crops at a 4:2 row ratio recorded more returns per unit cost incurred for production apart from niger.

3.5. Intercropping Indices

In this investigation, LER and ATER were greatly influenced by intercropping and row proportions (

Table 5. The efficiency indices of the finger millet intercropping system (grouped data of three years).

Treatments	LER	ATER	PUE	LUE (%)	RVT
T1: Finger millet + Field bean (4:2)	1.14	1.04	10.06	108.99	0.92
T2: Finger millet + Field bean (6:2)	0.91	0.80	8.63	85.47	0.77
T3: Finger millet + Horse gram (4:2)	1.41	1.33	11.72	136.88	1.01
T4: Finger millet + Horse gram (6:2)	1.14	1.06	9.45	109.68	0.82
T5: Finger millet + Groundnut (4:2)	1.64	1.38	13.99	150.78	1.37
T6: Finger millet + Groundnut (6:2)	1.41	1.14	12.70	127.22	1.21
T7: Finger millet + Niger (4:2)	1.03	0.93	8.75	98.14	0.81
T8: Finger millet + Niger (6:2)	1.08	1.00	10.06	104.09	0.90
T9: Sole crop of Finger millet	1.00	1.00	25.83	100.00	0.00
T10: Sole crop of Field bean	1.00	1.00	5.82	100.00	0.00
T11: Sole crop of Horse gram	1.00	1.00	4.27	100.00	0.00
T12: Sole crop of Groundnut	1.00	1.00	8.28	100.00	0.00
T13: Sole crop of Niger	1.00	1.00	2.86	100.00	0.00

(LER—land equivalent ratio; ATER—area time equivalent ratio; PUE—production use efficiency; LUE—land use efficiency; RVT—relative value total).

). LER values were found to be greater than unity, representing more land use efficiency under intercropping with different companion crops. Intercropping millet with groundnut at a 4:2 ratio showed a significantly higher LER (1.64), followed by finger millet + horse gram at 4:2 and finger millet + groundnut at 6:2. However, ATER values were also superior to unity with all the samples intercropping except the finger millet + niger (4:20) and finger millet + field bean (6:2). Finger millet + groundnut at a row ratio of 4:2 showed a significantly higher ATER (1.38) representing the highest advantage of temporal and spatial compared to other intercropping and row proportions. Finger millet sole cropping (25.83) showed a higher production use efficiency (PUE), as related to the intercropping system. Among the intercropping systems, the finger millet + groundnut at a 4:2 row ratio showed a significantly higher PUE (13.99), while the lowest value was documented with the finger millet + field bean (6:2; 8.63). Similarly, higher LUE and RVT were noticed in finger millet + groundnut at a 4:2 row ratio (150.78 and 1.37, respectively), succeeded by finger millet with groundnut at a 6:2 row ratio and finger millet with horse gram at a 4:2 row ratio.

3.6. Energy Analysis

The energy consumption for the cropping system is computed and accessible in

Table 6. Total energy input, output, and energy indices of the finger millet-based intercropping system (grouped data of three years).

Treatments	Energy Input (MJ/ha)	Energy Output (MJ/ha)	Energy Efficiency	Net Energy Gain (MJ/ha)	Energy Profitability
T1: Finger millet + Field bean (4:2)	12,359	56,883	4.61	44,523	3.61
T2: Finger millet + Field bean (6:2)	12,347	59,932	4.86	47,584	3.86
T3: Finger millet + Horse gram (4:2)	12,325	54,964	4.46	42,639	3.46
T4: Finger millet + Horse gram (6:2)	12,300	61,011	4.97	48,711	3.97
T5: Finger millet + Groundnut (4:2)	12,750	60,378	4.74	47,628	3.74
T6: Finger millet + Groundnut (6:2)	12,656	62,279	4.93	49,623	4.93
T7: Finger millet + Niger (4:2)	12,145	39,465	3.23	27,320	2.23
T8: Finger millet + Niger (6:2)	12,172	43,988	3.61	31,816	2.61
T9: Sole crop of Finger millet	12,204	72,432	5.95	60,227	4.95
T10: Sole crop of Field bean	9318	24,572	2.63	15,254	1.63
T11: Sole crop of Horse gram	5743	24,700	4.26	18,958	3.26
T12: Sole crop of Groundnut	10,836	60,857	5.55	50,021	5.14
T13: Sole crop of Niger	7340	14,477	2.26	7136	0.98

. The highest energy was used by finger millet sole cropping among the cropping systems in the present trial (12,204 MJ ha⁻¹) related to sole cropping; however, it was closely followed by groundnut sole cropping (10,836 MJ ha⁻¹). For the production process, the sole cropping of field bean, horse gram, and niger resulted in less energy spent. Amid different intercropping systems, a 4:2 row ratio (finger millet + groundnut) exhibited a higher consumption of energy (12,750 MJ ha⁻¹), which was comparable to the finger millet + groundnut at a 6:2 row ratio (12,656 MJ ha⁻¹). Finger millet as a sole crop recorded with the maximum output of energy (72,432 MJ ha⁻¹) due to higher biological yield related to the rest of the cropping systems. The finger millet + groundnut in intercropping systems at both row proportions showed higher energy output. Furthermore, the sole cropping of groundnut had a higher output energy (60,857 MJ ha⁻¹) than field bean and niger, while the lowest energy was noticed in the sole cropping of field bean (24,572 MJ ha⁻¹). Regardless of the cropping system and crops, nutrition (fertilizers and manures) used a higher quantum of energy, and the next order included fuel and machinery utilized in the production process of the cropping system (Figure 1). The energy efficiency (5.95) was found to be highest under finger millet sole cropping, and the following was the sole cropping of groundnut (5.55). Among the intercropping systems, the finger millet + groundnut cropping system at a 6:2 row ratio seemed to be the utmost energy efficient (4.97), which was analogous to finger millet + horse gram at a 6:2 row ratio. Net energy gain was accounted for, and the maximum was with the finger millet sole crop (60,227 MJ ha⁻¹), while energy profitability was noticed under the sole crop of groundnut (5.14). Among the intercropping systems, finger millet + groundnut at both ratios have recorded higher net energy gain and energy profitability, while finger millet + niger at a 4:2 row ratio has been observed with lesser values.

3.7. Indices of Carbon and Carbon Footprint

The different cropping systems’ carbon indices are presented in

Table 7. Carbon input, carbon output, net carbon gain, carbon efficiency ratio, and carbon efficiency of finger millet-based cropping system.

Treatments	Total Carbon Input (kg CE ha−1)	Total Carbon Output (kg CE ha−1)	Net Carbon Gain (kg CE ha−1)	Carbon Efficiency Ratio	Carbon Efficiency (kg−1 CE)
T1: Finger millet + Field bean (4:2)	381	2009	1627	5.29	5.34
T2: Finger millet + Field bean (6:2)	410	1801	1391	4.39	4.07
T3: Finger millet + Horse gram (4:2)	329	2334	2004	7.48	7.14
T4: Finger millet + Horse gram (6:2)	386	2063	1676	5.35	4.73
T5: Finger millet + Groundnut (4:2)	389	2842	2453	7.38	7.93
T6: Finger millet + Groundnut (6:2)	387	2506	2119	6.54	7.10
T7: Finger millet + Niger (4:2)	378	1774	1395	4.73	4.49
T8: Finger millet + Niger (6:2)	379	2113	1734	5.64	5.23
T9: Sole crop of Finger millet	379	2647	2268	7.08	6.12
T10: Sole crop of Field bean	255	258	3	1.01	3.50
T11: Sole crop of Horse gram	105	187	82	1.78	4.61
T12: Sole crop of Groundnut	277	440	163	1.59	4.43
T13: Sole crop of Niger	189	122	−66	0.65	2.79

. The finger millet, field bean, horse gram, groundnut, and niger as sole crops have relatively lower carbon inputs compared to intercropping. Among intercropping systems, the highest carbon input was noticed in the finger millet + field bean (6:2) system (410 kg CE ha⁻¹), and the lowermost was 329 kg CE ha⁻¹ under the finger millet + horse gram (4:2) system. The output data disclosed that finger millet + groundnut (4:2) showed a higher output of carbon (2842 kg CE ha⁻¹) related to other intercropping systems and sole cropping and was followed by the monoculture of the finger millet (2647 kg CE ha⁻¹) (Table 7). The carbon output was pointedly improved owing to the intercropping system because of the higher output of carbon under finger millet and groundnut. The maximum net carbon gain (2453 kg CE ha⁻¹), along with the higher efficiency ratio of carbon (7.38), was perceived in finger millet + groundnut at 4:2 row proportions. Owing to a moderately higher carbon output ratio over the input, finger millet + groundnut presented higher carbon efficiency (7.93) and niger as a sole crop (which showed a net carbon loss of −66 kg CE ha⁻¹), indicating poor carbon sequestration capacity.

4. Discussion

Intercropping is beneficial as it gives assurance towards greater resource use efficiency, dropping detrimental biotic agents and ensuring higher production and system sustainability [28,29]. In intercropping, harmony among cultivated species is imperative for enhancing crop productivity [30,31]. The adoption of the cropping system in dryland situations offers an expected cover averse to crop disaster [32]. Finger millet is a vital crop of dryland due to its ability to withstand stress and cultivate under poor and marginal soils. Companion crops like field bean, horse gram, groundnut, and niger were chosen in the intercropping system because these crops have growth habits that complement with finger millet, reducing the struggle for resources. Intercropping with a suitable companion crop in the optimum row proportion will lead to higher profitability and sustainability [33]. This investigation, therefore, stresses the prospect of the finger millet-groundnut cropping system concerning yield, energy, and economics.

Crop yield with all sole crops in the present investigation is superior to intercropping, and this is owing to the low resource struggle with sole cropping [34]. MGEY provides particulars of cropping system productivity with divergent produce, and prices were further worked out to identify system productivity. Finger millet + groundnut at 4:2 and 6:2 ratios showed 38.69 % and 22.32% higher productivity, respectively, than finger millet sole cropping for better habitation mutuality. The competitive productivity of groundnut was owing to low-growing habits, which complement the upright growth of finger millet, leading to the efficient use of light and space; groundnuts can also explore different soil depths, reducing direct competition for nutrients and water compared to other component crops. Therefore, groundnut showed 44.46%, 150.55%, and 219.63% more yield related to field bean, horse gram, and niger under sole cropping. The finger millet beneficial association was found when it was intercropped with groundnut in plain areas of semi-arid dryland, as stated by CRIDA in 2002. Finger millet yield attributes were reduced considerably when cultivated with companion crops compared to the sole finger millet, as conveyed by [35,36,37]. Finger millet and groundnut intercropping overall cropping systems have been noted to have higher yield attributes.

Under intercropping, the mutual nature in the crop mixture was further explicit through analyzing indices of intercropping, for instance, LUE, LER, PUE, and ATER, besides RYT. In this investigation, all the intercropping systems showed LER to be more than one or unity, representing the higher efficiency of land use in intercropping with different companion crops. However, LER of 1.64 was observed with finger millet + groundnut at the row ratio of 4:2, which was considered higher, indicating that 64% additional resource utilization for intercropping compared to sole cropping because of the complementary use of resources which reduced the competition and allowed nutrients, soil, and light to be utilized more efficiently than sole cropping. LER, more than unity, indicated that intercropping is advantageous [38]. Similarly, ATER provides a holistic measure by considering both temporal and spatial features. In this study, finger millet + groundnut at a row ratio of 4:2 showed a significantly higher ATER (1.38), indicating uppermost spatial and temporal gain with the finger millet and groundnut blend at a 4:2 row ratio related to the rest of intercropping and row proportions. Land use efficiency, relative economic efficiency, and the relative yield total were higher under finger millet + groundnut at a 4:2 ratio owing to the positive interaction between the finger millet and groundnut. The gross return, which was found to be the highest, was Rs. 116,782 ha⁻¹, and net returns came to Rs. 73,276 ha⁻¹, which was noticed with finger millet + groundnut at a 4:2 row ratio related to sole and the rest of the intercropping systems. The reason for this was ascribed to increased grain and straw yield with the system of finger millet and groundnut. Such findings conform with [8,39]. The higher benefit is accredited to higher yield, the higher market price of companion crops, and lower cultivation cost of intercropping reported by [40] in finger miller—groundnut strip cropping.

Energy consumption was seen to be higher under finger millet + groundnut at both row proportions due to the higher complexity in the management of both crops, such as managing pests and weeds and high labour demand for harvesting and post-harvest handling, leading to energy-intensive practices (Table 6). The higher output of energy (72,432 MJ ha⁻¹) was shown by finger millet sole cropping, and the next was finger millet + groundnut, accounting for its higher biological yield, whereas lower biomass production and the short growing season in niger were shown to have the lowermost output of energy (14,477 MJ ha⁻¹). Amongst intercropping systems, finger millet + groundnut at 6:2 row proportion (62279 MJ ha⁻¹) along with finger millet + groundnut at 4:2 row ratio (60,378 MJ ha⁻¹) produced higher energy output caused by complementary growth habits and higher biological yield in the overall system and was substantiated earlier by [20]. Similar findings were reported by [22] in fodder maize, [41] in forage cropping systems, and [42] in the soybean–wheat cropping system. Furthermore, efficiency of energy, net gain energy, and profitability of energy were high under finger millet association with groundnut at 6:2 (4.93, 49,623 MJ ha⁻¹ and 4.93, respectively) and was slightly comparable to finger millet and groundnut intercropping by 4:2. The sole cropping system of finger millet demonstrated higher energy efficiency because it produced more output relative to the energy invested compared to intercropping systems. Thus, productivity per unit of energy invested was maximized.

Finger millet intercropping with groundnut and horse gram demonstrated higher carbon output and net carbon gain compared to sole cropping (Table 7). This was owed to higher biomass production in relation to other systems. This highlights the potential of intercropping as a more sustainable and carbon-efficient agricultural practice. The catalogue of carbon emissions, input-wise, illustrates that the main causes of CO₂ emissions under both monoculture and intercropping systems are farmyard manure and machinery (Figure 2). Again, owing to the higher gain of carbon, carbon efficiency with finger millet with groundnut and horse gram intercropping, accordingly, expressed a similar higher efficiency of carbon for the comparatively higher output of the carbon over per unit carbon input used in the process of production. Carbon input and output are primary determinants of a production system that determine the efficiency [41]. Increased carbon output is always the result of improved biological yield [42,43]. Consequently, we found that finger millet + groundnut had a greater carbon efficiency ratio in our investigation, which produced the most carbon output per unit quantity of carbon intake, thus emerging as a carbon-efficient system. The finger millet and groundnut intercropping system (4:2 ratio) exhibited higher carbon efficiency, indicating its greater potential for carbon sequestration and environmental sustainability, even if its energy efficiency was lower than the sole crop of finger millet.

This study enhances the understanding of intercropping systems by presenting empirical evidence on the advantages of the finger millet and groundnut intercropping system. While much of the existing research has concentrated on monocropping or traditional farming methods, our findings broaden the theoretical foundation of resource-efficient agricultural practices. From a practical standpoint, the research provides important insights for smallholder farmers on how to boost crop yields, enhance profitability, and boost the efficient use of energy and carbon. This research makes a significant contribution to both the theoretical knowledge and practical application of agricultural sustainability.

Simple Linear and Multiple Regression Study

Even though correlation stretches facts around the nature of the relationship, which exists amid diverse variables, the relationship significance and the level are not defined clearly [44]. Henceforth, for enumerating the degree of influence of diverse variables over the dependent factor, such as grain yield, linear regression among an illustrative variable and a described variable is used. Between the total NPK uptake and yield, linear regression is revealed in Figure 3. This displayed the greatest impact of nutrient uptake and grain yield in all millet-based intercropping systems. Bestowing to the estimated influence, the uptake of total nitrogen documented 94% of the grain yield. Likewise, total phosphorus and potassium uptake accounted for 98% each. Multiple regressions between the grain yield of the finger millet and NPK uptake show a significant positive relationship.

Although the study offers valuable insights into the effectiveness of the intercropping system of finger millet and groundnut in a 4:2 proportion, there are certain limitations to consider as well. The research was conducted in specific agro-climatic conditions, which may not fully represent other regions with different environmental factors. Additionally, the long-term effects on soil health were not evaluated. Limitations in resources also restricted the scope of the experiment. Despite these limitations, the findings have significant practical implications. The intercropping system offers a promising solution for improving resource use efficiency, enhancing farm profitability, and promoting sustainable agricultural practices, particularly in semi-arid regions. By optimizing land, water, and nutrient use, this system can increase both productivity and environmental sustainability. Moreover, these results can guide agricultural policies and extension services aimed at supporting smallholder farmers and promoting climate-resilient farming systems in similar agro-climatic zones.

Future research should consider evaluating the long-term effects of the intercropping system on soil fertility, water use efficiency, and overall ecosystem health. Additionally, similar studies could be conducted in different agro-climatic zones to assess the adaptability of the system to varying environmental conditions.

5. Conclusions

The various cropping systems’ overall performances for productivity, profitability, and efficiency in resource use were consecutively studied for three years. The sole cropping of finger millet showed a superior yield performance related to intercropping. Also, higher yields were displayed through companion crops compared to sole cropping. Among the companion crops, groundnuts exhibited a higher yield than other crops. Finger millet + groundnut at a 4:2 row proportion was found to be a more beneficial intercropping system by exhibiting a significantly higher main crop grain equivalent yield (3065 kg ha⁻¹) and net returns (INR 73,276 ha⁻¹) associated with other intercropping systems. Finger millet intercropping was evidenced to be more efficient in terms of time and land compared to sole cropping by showing ATER and LER values of more than unity. Furthermore, finger millet + groundnut at a 4:2 row ratio noticed a higher LER (1.64), ATER (1.38), LUE (150.78%), and RVT (1.37) in contrast over other cropping systems. Finger millet sole cropping displayed a higher output of energy (72,432 MJ ha⁻¹), energy efficiency (5.95), net gain energy (60,227 MJ ha⁻¹), and energy profitability (4.95) than other cropping systems. Among intercropping, finger millet + groundnut at both row proportions of 4:2 and 6:2 was found to be superior for energy output, net energy gain, and the profitability of energy than other companion crops within the finger millet cropping system. Intercropping finger millet with groundnut and horse gram has demonstrated superior carbon sequestration competencies, making them more sustainable and carbon-efficient options compared to sole crops like niger, which showed net carbon loss. Thus, the current study has established that the intercropping of finger millet with groundnut may significantly enhance overall agricultural productivity, economic profitability, efficiency of energy use, and carbon.