Conservation Agricultural Practices for Improving Crop Production and Quality

1. Introduction

Modern agriculture faces many challenges, the most important of which are the effects of climate change, soil degradation and fertility decline, pressure on water resources, and food insecurity. In this context, it is crucial to increase crop production while reducing negative environmental impacts. One approach that favors the sustainable intensification of production is the use of conservation agriculture (CA) practices, which include various techniques that reduce the depth and intensity of mechanical tillage (strip-till, no-tillage, reduced tillage) and associated practices (cover crops, mulching, crop rotation, cultivar selection) [1,2]. CA aims to maintain the natural soil structure, reduce erosion and improve the water balance and organic matter content of soil to improve crop yield and quality [3]. The primary purpose of this Special Issue was to assemble studies that demonstrate the research progress on agricultural practices that combine the high production of quality raw materials with the provision of environmental services.

2. The Influence of Conservation Agricultural Practices on Soil Properties

With the worsening of the effects of climate change and increasing pressure on water resources, there is a growing need for adaptive management strategies, such as CA, which could be beneficial for soil quality and water use efficiency. However, the effectiveness of CA can vary considerably depending on the practice implemented and soil and climatic conditions [4], with the short-term effects of this farming system differing significantly from those observed in long-term studies [5].

In a study conducted in Mediterranean climatic conditions, Dominguez-Bohorquez et al. showed that CA practices, such as no-tillage (NT), cover crops (CC) and crop rotation, applied under irrigated and non-irrigated conditions from the first year, clearly affected soil properties, water flow and crop yields (maize, sorghum and soybean). Conservation agricultural practices resulted in increased bulk density and soil resistance penetration, leading to decreased quasi-steady ponded infiltration in the surface horizon. This phenomenon was observed especially under subsurface-drip-irrigation and no-irrigation conditions. Crop residues in this cropping system reduced soil water evaporation, especially under sprinkler irrigation, but this benefit decreased as crop residues decomposed. In a study by Alhammad et al., NT accompanied by crop residues significantly improved soil chemical and biological properties by increasing soil organic carbon content, improving nutrient availability and increasing microbial populations, such as Azotobacter, Pseudomonas and Bacillus. The results of their research indicated that using the transplanting method for rice, followed by NT for wheat and green gram, increases yields, profitability and soil health.

In saline alluvial meadow soils of an arid region, Nurbekov et al. showed that the application of NT combined with legume-based short crop rotation resulted in higher retention of crop residues (by 20.9%) and root residues (by 25%) than in the conventional system, with beneficial effects on soil structure and soil carbon (C), nitrogen (N) and phosphorus (P) abundance. In this cropping system, increased retention of crop residues had a beneficial effect on soil porosity, structural stability and water retention, while soil salinity in the 0–25 cm and 75–100 cm soil profiles and soil temperature were reduced. According to the authors, the application of the NT system can counteract ongoing land degradation in dryland areas affected by salinity.

Wilczewski et al., in a review article, highlight the positive effects of CA, particularly the presence of CC, on the physical, chemical and biological properties of soil. The authors indicate an increase in soil microbial abundance and an improvement in soil enzyme activity with reduced tillage (RT). In addition, CC biomass increases the capacity of the sorption complex, which has a beneficial effect on soil moisture. CC cultivation is perceived by farmers as an effective way to improve soil structure and increase soil organic matter content and is becoming a regular part of farming in Finland, as indicated by a survey conducted by Peltonen-Sainio et al.

The importance of straw return as an effective management practice to improve the physical and chemical properties of saline–sodic soils in Northeast China was highlighted by Xie et al. They showed that in rice cultivation, carrying out straw return in the autumn is more efficient than doing so in the spring, as there is a longer and slower decomposition period. Akwakwa and Xiaoyan describe the positive effect of rice–wheat straw incorporation, combined with different nitrogen rates, on soil physico-chemical properties in the Jianghan plain of the Yangtze River basin (China). The authors showed that the incorporation of straw into the soil, combined with N fertilization, leads to varying levels of soil N, P, nitrate (NO₃⁻), ammonium (NH₄⁺), potassium (K), moisture, and pH, as well as wheat grain yield. In addition, the introduction of straw reduced soil bulk density and increased water retention.

3. The Impact of Conservation Agriculture Practices on the Quantity and Quality of Crop Yields

Improving the physical, chemical and biological properties of soil through CA practices can have a positive impact on yield quantity and quality, although this is also dependent on climatic conditions, soil type and crop species. Adequate management of crop residues and CC is also crucial to the effectiveness of CA. The literature reports that during the initial period of implementing CA practice, crop yields may be lower compared to conventional plow cultivation (CON), which may be due to a slower rate of N mineralization and accumulation of organic matter mainly in the surface soil layer, resulting in lower plant nutrient availability [6]. This is confirmed by the study of Nieman et al., who obtained a lower or similar yield of sorghum (depending on weather conditions) when implementing NT compared to cultivation with a chisel plow. The authors attributed the decrease in yield in dry years to a shortage of water during germination and plant emergence, while in years with more rainfall, the yield did not depend on the cropping system.

The literature reports that, in the long term, CA stabilizes organic matter content and improves the relationship between soil structure and water, resulting in increased yields and improved crop quality [7,8]. This is confirmed by the results presented by Dong et al., who showed an increase in the weight of 1000 grains and the number of grains per spike for winter wheat grown through NT compared to CON, which the authors attribute to higher soil moisture at a depth of 20 cm at the grain-filling stage. Although the number of wheat ears when implementing NT was 10.8% lower, the grain yield was 2.7% higher than that when implementing CON. The beneficial effect of higher soil moisture using CA on plant yield was demonstrated by De Santis et al. in a year with limited rainfall; growing durum wheat through NT increased its yield by 15%, improved its grain quality and led to a higher economic return compared to that grown through CON. Also, in the study by Nurbekov et al., compared to crops grown through CON, the NT cultivation of winter wheat, millet, chickpea and maize in rotation in saline alluvial meadow soils of the arid region in Uzbekistan resulted in a significant, sustained increase in the yield of all species grown in two 3-year cycles. In addition, the authors demonstrated the beneficial effects of NT on the soil environment, and concluded that the NT system plays an important role in sustainable land management in arid areas.

4. Integration of Conservation Agricultural Practices with Breeding of Resistant Varieties

CA benefits the soil environment by reducing degradation, improving fertility and increasing water retention, but its effectivity can be limited by various abiotic stresses, such as drought or salinity. The selection of cultivars with increased stress tolerance is therefore an important component of CA implementation [9,10,11].

Modern plant breeding adapted to cultivation in conservation systems focuses on sowing cultivars with a deep, strong and well-developed root system so that plants can effectively utilize water stored in deeper soil layers and their roots can easily penetrate compacted soil layers [12]. A study by Choi et al. showed that the late-flowering sorghum cultivar Greenstar had a stronger root system that made better use of available soil resources even at lower N rates compared to the earlier-flowering cultivar Honeyew. Better root development and higher rates of root survival are features that can be used in NT.

Soil salinity is a major agricultural problem, especially in areas with limited water availability. In NT, an increase in salinity is observed, especially in the topsoil, so breeding cultivars resistant to this stress factor is crucial to increase the stability of crop yields. Gerakari et al. analyzed the potential of using wild relatives of tomato to improve yield size and quality under high-soil-salinity conditions. Of the nine genotypes, the line IL6-6 showed the highest stress tolerance, maintaining stable photosynthetic parameters, yield levels and fruit quality even at the highest salinity levels. These results indicate that this genotype could be valuable for breeding salinity-tolerant cultivars. Also noteworthy is a study by El-Ata et al., in which the authors analyzed genotype–environment interaction. The study showed that the yield level of twelve rice cultivars was mainly determined by environmental conditions (sowing date, weather conditions), with two cultivars showing greater yield stability under different conditions compared to other cultivars; these can also be used in breeding programs that take into account the adaptation of cultivars to changing conditions.

5. Conclusions

CA comprises agricultural practices that benefit soil’s fertility and properties and increase the efficiency of crop production in a sustainable manner. The results of the articles in this Special Issue demonstrate that the use of CA practices, such as NT, RT, mulching, CC and diversified crop rotations, significantly affect the physical, chemical and biological properties of soil, improve soil water retention and increase the macronutrient content available to plants. In addition, CA affects yield quantity and quality, producing high and stable yields in the long term. The use of CA has also been found to be particularly valid in environments exposed to abiotic stresses, such as drought or salinity, and the combination of CA with the breeding of cultivars with higher stress tolerance makes it possible to increase the efficiency and stability of crop production in a sustainable manner.