Next Article in Journal
Path Tracking Controller and System Design for Agricultural Tractors Based on Improved Stanley and Sliding Mode Algorithms Considering Sideslip Compensation
Previous Article in Journal
Transcriptome Analysis Revealed the Molecular Mechanism of Cyanogenic Glycoside Synthesis in Flax
Previous Article in Special Issue
The Effect of Nitrogen Fertilizer Placement and Timing on Winter Wheat Grain Yield and Protein Concentration
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Agronomy
Volume 15
Issue 10
10.3390/agronomy15102328
agronomy-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Productivity and Forage Quality of Alfalfa Response to Potassium Fertilizer: A Field Study in Inner Mongolian Plateau

by
Yuntao Wang
1,
Lele Cui
2,
Shenghao Liu
2,
Wenxuan Li
1,
Zhenyi Li
1,
Wenxing Ye
1 and
Linqing Yu
2,*
1
College of Grassland Science, Inner Mongolia Agricultural University, Hohhot 010011, China
2
College of Life Science, Inner Mongolia University, Hohhot 010019, China
*
Author to whom correspondence should be addressed.
Agronomy 2025, 15(10), 2328; https://doi.org/10.3390/agronomy15102328
Submission received: 2 September 2025 / Revised: 28 September 2025 / Accepted: 30 September 2025 / Published: 1 October 2025
(This article belongs to the Special Issue Fertility Management for Higher Crop Productivity)
Browse Figures
Review Reports Versions Notes

Abstract

The Inner Mongolian Plateau is a critical region for the development of herbivorous animal husbandry in China. However, its harsh climate and poor soil quality have constrained the sustainable growth of the alfalfa industry. This 3-year field study investigated the effects of potassium (K) fertilizer on the productivity and forage quality of alfalfa (Medicago sativa L. cv. ‘WL168’) in such specific conditions of the region. Five rates of K fertilizer (0 (CK), 100, 200, 300, and 400 kg ha−1 of K2O) were applied in three split applications. Forage harvests occurred three times annually in 2023 and 2024, and yield, yield components, and forage quality were determined. The results showed that the forage yield of alfalfa increased initially and then decreased with the rising K application rates, which paralleled the changes in the plant density, and plant height, especially the mass shoot−1; forage yield was mainly correlated with mass shoot−1. Appropriate K fertilizer improved forage quality, especially in 2024. With increasing application, crude protein (CP) and total digestible nutrients (TDNs) first rose then declined, whereas neutral detergent fiber (NDF) and acid detergent fiber (ADF) decreased steadily, leading to a consistent rise in the relative feeding value (RFV). Comprehensively considering both yield and quality under such condition, a K fertilizer application rate of 273.2 kg ha−1 of K2O is suggested as a reference for this region.

1. Introduction

Potassium (K) is an essential mineral nutrient for plant growth and development, and represents the most abundant cationic element in plants, typically comprising 2–10% of their dry mass [1]. Within plant tissues, K fulfills diverse physiological roles. In addition to regulating stomatal aperture and activating enzymes involved in photosynthesis, K facilitates the transport of ATP, proteins, starch, phenolic compounds, and sugars, and contributes to cellulose synthesis, water and nutrient movement, and biological nitrogen fixation [2]. Consequently, K deficiency is associated with reduced plant growth, diminished yield, impaired nutrient availability, compromised cell wall formation, and decreased resistance to abiotic stresses [3,4].
As a major agricultural country, China faces severe K scarcity in much of its cultivated land due to long-term over-farming, improper fertilizer application, and other contributing factors. Recent statistics indicate that 23% of China’s farmland is K-deficient [5]. Compounding the problem, the global K fertilizer market is highly monopolized, and continued increases in international prices have further constrained domestic supply. Consequently, the availability of K fertilizers in China has been severely limited, exacerbating the already critical shortage of K in arable soils and significantly impairing crop yields [6].
Alfalfa (Medicago sativa L.) has a particularly high demand for potassium (K), which exceeds its requirements for other mineral elements. It extracts approximately 250 kg of K per hectare annually from the soil, with higher-yielding stands removing even greater amounts of nutrients [7]. K significantly enhances rhizobial nitrogen fixation in alfalfa and plays a critical role in promoting plant growth, improving resistance to diseases and pests, and strengthening lodging resistance. Generally, young alfalfa plants exhibit higher K content compared to mature plants. Long-term cultivation of alfalfa typically leads to substantial depletion of soil K reserves [8]. Inadequate K availability has been associated with reduced alfalfa stand persistence and increased weed infestation in alfalfa fields [9,10,11,12]. Therefore, effective K fertility management is essential for achieving high yields and quality in alfalfa production, particularly in soils with low to moderate K levels [2,13,14]. Applying K fertilizer under these conditions can enhance yield and stand longevity, especially in older stands [11]. Adequate K nutrition supports increased plant population density and shoot biomass, and is necessary for sustaining high forage yields over multiple growing seasons [12]. Relying solely on the limited naturally available soil nutrients is insufficient to meet alfalfa’s demands, making supplemental fertilization necessary [15].
The Inner Mongolia Plateau is a crucial base for animal husbandry in northern China, with a substantial demand for forage. Fully utilizing local land resources to develop the alfalfa industry is essential for ensuring the sustainable development of animal husbandry in the region. In particular, implementing a crop rotation system—such as planting alfalfa for three years followed by potato cultivation—can enhance soil fertility and resource use efficiency. However, the cold climate and poor soil quality of the Inner Mongolia Plateau constrain alfalfa’s winter survival and limit its potential for high yield. This region is characterized by a temperate continental monsoon climate with severe winters, significant diurnal temperature variations, frequently occurring late spring coldness, strong wind, and a short frost-free period. Annual precipitation is low and highly erratic, mainly in summer, while potential evaporation rates are 8–10 times higher, creating a persistent water deficit [16,17]. The predominant soils are sandy loams with inherent low fertility, characterized by low organic matter content, high pH, and susceptibility to salinization, which further challenges alfalfa production [18,19].
Adequate fertilizer supply plays a key role in enhancing both the cold resistance and productivity of alfalfa. If less or no fertilizer is applied, the yield persistence of alfalfa decreases, which could also negatively affect subsequent crops like potato in the rotation system. How to maintain the alfalfa yield on the K-fertility-limited planting area through reasonable fertilization is an urgent and important issue to be solved, especially within the context of such a rotation framework. Our objectives were (i) to determine the impact of fertilizer on the yield and yield components of alfalfa; (ii) to explain the effects of K fertilizer on forage quality of alfalfa; and (iii) to clarify a suitable fertilizer application rate that synergistically improves alfalfa forage yield in the Inner Mongolian Plateau under this alfalfa–potato rotation system.

2. Materials and Methods

2.1. Field Experimental Site

The field experiment was carried out at Alfalfa Breeding Base of Inner Mongolia University, located 100 km north of Hohhot, China (41°54′ N, 111°45′ E, 1495 m above sea level). The research site was sandy loam soil and had been used for alfalfa seed production for five years and fallow for one year. The mean annual air temperature is 2.9 °C, and the annual precipitation is about 200 mm, primarily concentrated in June, July, and August. The evaporation rate is 8 to 10 times higher than the precipitation. The temperature difference is significant, with drastic changes in spring and autumn, frequent windy days, and a short frost-free period of approximately 110 days. Sunshine duration ranges from 3084 to 3286 h. Soil samples collected from the 30 cm depth were analyzed following Liu et al. [20]: 1.72% organic matter, total nitrogen of 1.07 g kg−1, total phosphorus of 0.44 g kg−1, total potassium of 22.66 g kg−1, available nitrogen of 65.20 mg kg−1, available phosphorus of 14.70 mg kg−1, available potassium of 125.30 mg kg−1, Mg of 346.58 mg kg−1, Ca of 2.44 g kg−1, and 8.5 pH. The average air temperatures and precipitation during the experiment are shown in Table 1.

2.2. Experimental Design and Sampling

The alfalfa variety used in the experiment was WL168 (FD 2, suitable in dry and cold areas), which was brought from Beijing Rytway Ecotechnology Co., Ltd. (Beijing, China). The experimental design was a randomized complete block with the fertilizer amount treated as the only variable; each fertilization treatment was replicated three times. Firstly, the seeds were planted by hand into 3 × 5 m field plots on late Jule 2022, the sowing rate was 22.5 kg ha−1, with 30 cm rows, and 1~2 cm depth. A 1 m width of WL 168 around the experimental site was used as border rows. Secondly, five application rates of K fertilizer (0 (CK), 100, 200, 300, and 400 kg ha−1 of K2O applied as K2SO4 (52% K2O)) were used in split doses according to a ratio (50% in the October of the establishment year, with the remaining 25% applied after the first and second cuttings in the following year, respectively), which was produced by HSDIC Xinjiang Lop Nur Potash Co., Ltd. (Hami, China). Each fertilizer treatment was set up with three replicates. The fertilizer was incorporated at a depth of 5–8 cm between rows within plots to avoid burning the seedlings or roots. Irrigation was carried out after fertilization. No diseases or pests occurred during the experiment. Weeds were controlled by mowing or hoeing in the year of establishment and in the spring of 2023 and 2024. There were no harvests in the establishment year [21].
The plots were irrigated both in spring during green-up and after the first two harvests in 2023 and 2024, as well as during the growing periods with no rainfall for approximately ten days. The irrigation method employed was drip irrigation, with each irrigation amount being approximately 50 mm. Three harvests were obtained each year: the first two cuts were at the early flowering stage, the third cut was conducted 30 days before the frost. At each harvest, the fresh weight was based on the 8.0 m2, and sampling was avoided on the borderlines to prevent marginal utility. A sample of 500 g fresh forage was oven-dried at 105 °C for 30 min, then at 65 °C for 48 h and re-weighed, and the dry-to-fresh ratio of the forage was determined. Then, the forage yield per hectare was calculated based on fresh weight, dry-to-fresh ratio, and area. A subsample of 50 shoots was hand-collected at approximately six randomly selected sites within each plot before harvest, oven-dried at 105 °C for 30 min, then at 65 °C for 48 h and weighed, and mass shoot−1 was determined [11,12]. Height shoot−1 was measured at ten randomly selected locations within each plot and the values were averaged to obtain one value [13]. Plants m−2 and shoots m−2 were calculated by counting the plants and shoots in the same 1 m2 at each harvest.
Nutritional indicators were measured using forage samples from the first harvest. The determination methods for crude protein (CP), Total Digestible Nutrients (TDNs), Neutral Detergent Fiber (NDF), and Acid Detergent Fiber (ADF) were performed according to Jungers et al. [2]. The relative feeding value (RFV) was calculated using the following formula based on the contents of NDF and ADF; RFV (%) = (88.9 − 0.779 × ADF) × (120/NDF)/1.29.

2.3. Statistical Analysis

Analysis of variance was performed on the data (forage yield, yield components, and forage quality indexes) to assess the effect of K fertility treatments on these parameters. The data were analyzed by one-way ANOVA, Tukey’s test and regression analysis with SPSS 26 software.

3. Results

3.1. Effects of K Fertilization on Forage Yield of Alfalfa

The application of K fertilizer positively influenced the forage yield of alfalfa (Table 2). In 2023, the forage yield from the first two harvests (H1 and H2) initially increased and then decreased with higher K fertilizer rates, while the yield of H3 continued to increase with increasing K application. The annual forage yield reached a maximum of 14,901.3 kg ha−1 at 200 kg ha−1 of K fertilizer, representing a 48.1% increase compared to the control. In 2024, the forage yields of H1 and H3 exhibited a trend of initial increase followed by a decrease with rising K fertilizer rates, whereas the yield of H2 increased consistently with higher application rates. The annual forage yield peaked at 17,326.8 kg ha−1 under 300 kg ha−1 of K fertilizer, which was 60.9% higher than the control.
Regarding the contribution of each harvest to the annual yield, H1 contributed the most, followed by H2, and H3 the least. In 2023, the proportion of annual forage yield from each harvest was 44.5%, 38.9%, and 16.6% for H1, H2, and H3, respectively. In 2024, the respective contributions were 44.5%, 33.3%, and 22.1%.
Taking the annual forage yield under different K fertilizer application rates as the dependent variable and the amount of K fertilizer application rates as the independent variable, the regression analysis was carried out, and the results are shown in Figure 1. The forage yield had obvious quadratic relationships with K fertilizer application rates, with R2 = 0.588 (p < 0.01). The optimal amount of K fertilizer for high alfalfa yield within two years is 273.2 kg ha−1, which came from the quadratic regression equation Y = 10,046.533 + 39.881x − 0.073x2.

3.2. Effects of K Fertilization on Yield Components of Alfalfa

3.2.1. Plant Density

The application of K fertilizer influenced alfalfa plant population density (plants m−2) to varying degrees (Figure 2). In 2023, the plants m−2 of alfalfa increased initially and then decreased with rising K fertilizer rates at each harvest. In 2024, a similar trend was observed in H1 and H2, whereas the plants m−2 of alfalfa in H3 continued to increase with higher K rates. H1 consistently exhibited the highest plant m−2 cross both years. Additionally, a gradual decline in plants m−2 was observed over the harvest sequence within each year.
In 2023, the plants m−2 of the control showed a 45.8% decrease from H1 to H3. In contrast, K-treated plots experienced smaller reductions, ranging from 15.1% to 36.5%. Similarly, in 2024, the control group declined by 27.9% from H1 to H3, while the decrease in K-treated alfalfa was less pronounced, ranging between 15.4% and 20.8%. Overall, ignoring the effect of K fertilizer, the total reduction in plants m−2 from H1 to H3 was 29.3% in 2023, and 19.9% in 2024.

3.2.2. Shoot Density

The application of K fertilizer influenced alfalfa shoot density (shoots m−2) to some extent (Figure 3). In 2023, the shoot density of alfalfa increased initially and then decreased with higher K fertilizer rates at each harvest. A similar trend was observed in 2024, with shoot density peaking at 300 kg ha−1 of K fertilizer in H1 (789.80 shoots m−2) and H3 (579.00 shoots m−2), and at 200 kg ha−1 in H2 (597.6 shoots m−2).
Comparing between years, shoot density in H1 was generally lower in 2023 than in 2024 across most K fertilizer treatments. In contrast, shoot density in H3 was higher in 2023 than in 2024 at all K levels. For H2, shoot density in 2023 exceeded that in 2024 at each fertilizer rate except under the control treatment.

3.2.3. Mass Shoot−1

The application of potassium (K) fertilizer influenced the mass per shoot (mass shoot−1) of alfalfa (Figure 4). In 2023, the mass per shoot initially increased and then decreased with increasing K fertilizer rates in the first two harvests (H1 and H2), reaching maximum values of 3.07 g and 1.41 g at application rates of 200 kg ha−1 and 300 kg ha−1, respectively. In contrast, the mass per shoot in H3 continued to increase with higher K fertilizer application. In 2024, a similar pattern of initial increase followed by decrease was observed in H1, reaching 2.79 g at application of 300 kg ha−1. However, both H2 and H3 exhibited a consistent increase in mass per shoot with elevating K fertilizer rates. Across both years, regardless of K fertilization, H1 consistently showed the highest mass per shoot, whereas H3 had the lowest.

3.2.4. Plant Height

The application of K fertilizer had certain effects on plant height (height shoot−1), with notable effects observed primarily during the first two harvests (H1 and H2) of 2023 and the first harvest (H1) of 2024 (Figure 5). In 2023, the height shoot−1 in H1 and H2 exhibited an initial increase followed by a decrease with rising K fertilizer rates. At an application rate of 300 kg ha−1, height shoot−1 increased by 41.8% and 55.3% compared to the control, respectively. In contrast, plant height in H3 showed no significant response to changes in K fertilizer. In 2024, a similar trend of initial increase and subsequent decrease was observed in H1 with increasing K fertilizer rates, whereas height shoot−1 in H2 and H3 remained largely unaffected.
Regarding comparisons among harvests: in 2023, height shoot−1 in H2 was generally greater than that in H1 across all K fertilizer treatments except the control, while H3 consistently had the lowest height shoot−1, regardless of K application. In 2024, height shoot−1 was greatest in H1, followed by H2, and lowest in H3, both with and without K fertilization.

3.3. Relationship Between Forage Yield and Yield Components

To comprehensively assess the contribution of each yield component to forage yield, a regression analysis was performed using plants m−2 (D), shoots m−2 (S), mass shoot−1 (SM), and height shoot−1 (H) from each harvest over two years as independent variables, with forage yield (Y) as the dependent variable (Figure 6). The regression equations for forage yield are as follows: Y = 3300.509 + 20.187 D (R2 = 0.078, p < 0.01, n = 90), Y = 2718.560 + 2.690 S (R2 = 0.125, p < 0.01, n = 90), Y = 1567.614 + 2122.399 SM (R2 = 0.739, p < 0.01, n = 90), Y = −1533.263 + 89.396 H (R2 = 0.630, p < 0.01, n = 90). Higher R2 values were obtained for mass shoot−1 and height shoot−1, indicating that these components may contributed more significantly to forage yield than plants m−2 or shoots m−2.

3.4. Effects of K Fertilization on Forage Quality of Alfalfa

Application of K fertilizer improved forage quality in both years, especially in 2024 (Table 3). In 2023, there was no significant effects of K fertilizer application on forage quality parameters (p > 0.05). However, numerical trends were noted: CP, TDN, and RFV showed a slight increase, while ADF and NDF exhibited a slight decrease compared to the control. In 2024, the CP and TDN first increased and then decreased with rising K fertilizer rates. The highest CP value was achieved at a K application rate of 200 kg ha−1, while TDN reached its peak at 100 kg ha−1. The RFV increased significantly with higher K fertilizer application. When the K application rate exceeded 200 kg ha−1, the RFV values surpassed 170, which were significantly greater than that of the CK (p < 0.05). Additionally, both ADF and NDF were significantly reduced compared to the CK following K fertilizer application (p < 0.05).

4. Discussion

4.1. Effects of K Fertilizer on Yield of Alfalfa

The high forage yield of alfalfa has long been the major goal pursued by farmers [22]. Alfalfa exhibits substantial demand for K, as K fertilization not only enhances nitrogen fixation and nodulation but also accelerates the synthesis and transport of assimilates with increasing soil K availability, thereby improving both yield and profitability [23]. Barbarick [24] reported that K application significantly increased dry matter yield in the first two years and total alfalfa yield over the entire study period in Colorado. Similarly, Burmester et al. [25] observed that spring K fertilization maintained stand density and increased forage yield in two-year-old alfalfa stands grown on Decatur silty clay loam and Hartsells fine sandy loam in northern Alabama, where initial soil test K levels were low to medium. Ma et al. [26] demonstrated that a single K fertilizer application in K-deficient soils of high-altitude regions in Southwest China promoted alfalfa growth rate, plant height, and increased forage yield by 21.7%. In Northeast China, Yang et al. [27] found that fresh forage yield of alfalfa initially increased and then slightly decreased with rising KCl application, with an optimal rate of 100 kg ha−1. Kang [28] also reported increased alfalfa yield in response to K fertilization, although the effect plateaued when K application reached 150 kg ha−1. In this study, the application of K fertilizer had positive effects on forage yield, and the optimal rate for achieving high yield in the first three years was determined to be 273.16 kg ha−1.
Proper application of K fertilizer can enhance alfalfa yield; however, excessive K fertilization may inhibit the absorption of other essential nutrients [29], and lead to a decline in forage production—a phenomenon known as the negative fertilizer effect. Over-application of K fertilizer can also contribute to soil salinity accumulation. This occurs primarily because commercial K fertilizers are largely water-soluble salts. Furthermore, when crops take up K+ ions, the accompanying anions (e.g., sulfate or chloride) may combine with cations such as calcium or sodium in the soil to form highly soluble compounds like sodium sulfate or calcium chloride, thereby increasing soil salt content [30,31]. Additionally, excessive K application can cause environmental pollution in soil and water systems and may reduce future crop productivity [32]. There is also concern that alfalfa may accumulate higher-than-necessary levels of K, which could adversely affect livestock health [33]. Therefore, avoiding excessive K fertilization is crucial to prevent yield reduction and fertilizer waste [15]. In this study, forage yield was higher in the second year than in the first, and fertilized plots significantly outperformed unfertilized ones. This suggests that split K application can have residual benefits extending over multiple years. Nonetheless, since alfalfa has a high demand for potassium, continuous K fertilization is recommended to sustain high forage yields.

4.2. Effects of K Fertilizer on Yield Components of Alfalfa

Alfalfa forage yield is determined by plants area−1, shoots plant−1, and mass shoot−1 [34]. Surviving plants are fundamental for yield formation, yet plant mortality is inevitable. Significant reductions in the alfalfa population following emergence have been documented, with most losses occurring during the growing season and fewer over winter [12,28]. Averaged across fertility treatments, plant population densities continuously declined from the first harvest (H1) in 2023 to the third harvest (H3) in 2024, with a more pronounced decrease observed in 2023. Notably, the application of K fertilizer mitigated population loss. This finding aligns with Stout et al. [35], who speculated that root and crown diseases were the cause of stand thinning during the growing season. In addition, plants that sustained winter injury often survived until the first harvest but subsequently died by mid-summer [11]. Competition for water, light, and nutrients during the growing season may also contribute to plant death [12], and the smallest plants in the population would preferentially die because of weak vitality and extensive shading from larger neighbors [36].
Adequate K nutrition is thought to increase plant persistence [37]. Berg et al. [11] reported that alfalfa fertilized with K, but not fertilized with phosphorus, exhibited higher plant population densities and improved persistence. Similarly, Collins et al. [10] conducted crown counts and observed a 50% decline in stand density between the first and second years in K-fertilized plots, compared to a 73% decline in unfertilized controls. The results of this experiment were consistent with those findings, demonstrating that appropriate K fertilizer application can enhance the persistence of alfalfa. However, Hanson and Macgregor [38] reported no association between variation in stand density (ranging from 37% to 62%) and forage yield. Although the plant density decreased from 2023 to 2024, the forage yield increased instead of decreasing. There was a linear regression relationship between plant density and forage yield, though the value of R2 was low. This phenomenon may be explained by compensatory growth within plant communities: as individual plants grow, their space requirements increase, leading to a self-thinning effect within the population [12]. White and Harper [39] supposed that plants established a hierarchy for determining resources, resulting in differential growth rates among competitors. Within populations exhibiting variable growth, suppressed individuals are eventually eliminated through competition, while dominant plants continue to thrive.
The plant density per unit area (plants area−1) and the number of shoots per plant (shoots plant−1) collectively determine the shoot density per unit area (shoots area−1). Alfalfa yield is positively correlated with shoots area−1, which can serve as a key criterion for deciding whether to maintain an existing alfalfa stand [11]. When adequate phosphorus and K fertilization are supplied, both shoots area−1 and forage yield can be sustained at higher levels over time [40]. Berg et al. [12] reported that although the application of K fertilizer significantly increased total forage yield, high yield was not solely dependent on high numbers of shoots m−2. In our study, an appropriate amount of K fertilizer increased shoots m−2 to same extent, although the shoots m−2 decreased in 2024 due to reduced plant population, annual yield was maintained at a consistent level. This indicates that while shoots plant−1 contributes to forage yield, it is not the predominant factor influencing overall production [12]. Alfalfa exhibits a compensatory mechanism between plant population and shoot number: when plant density decreases, the number of stems per plant can increase, thereby mitigating potential yield loss.
Increased mass shoot−1 has been consistently linked to improved agronomic performance in alfalfa, whether resulting from genetic selection, enhanced soil fertility, or effective insect control [11]. Previous researches have demonstrated a strong positive correlation between mass shoot−1 and forage yield [11,12,21], which was also proved by this study. The regression analysis revealed that mass shoot−1 made more contribution to forage yield than other yield components. Our findings agree with the results of Frakes et al. [41], who reported that stem and leaf weight (components of mass shoot−1) exerted a greater direct influence on yield than stem number (shoots plant−1). Cooper et al. [42] attributed that K fertilization could increase mass shoot−1, and achieved by increasing the number of leaves per shoot. In this study, mass shoot−1 in the first two harvests initially increased and then decreased with rising K fertilizer rates. In contrast, during the later growth stage (H3), which coincided with a period of cold accumulation, shoot growth was inhibited and no significant differences in mass shoot−1 were observed.
Two components determine mass shoot−1: height shoot−1 and mass shoot height−1 [43]. The increase in mass shoot−1 can be achieved though greater plant height, which itself has a significant direct effect on forage yield [21]. Plants receiving K initiated new shoot growth more rapidly and achieved a greater height than unfertilized plants, owing to enhanced nutrient mobilization between roots and actively growing shoots. This effect was mainly reflected in the first two harvests of 2023 and the first harvest of 2024. Furthermore, after shoot initiation, shoot development was improved under higher K fertility, resulting in increased mass shoot height−1 [44]. Therefore, cultivars genetically predisposed to producing larger shoots—rather than more shoots per crown—are likely to respond more positively to K fertilizer applications and achieve higher yields under well-fertilized conditions [11].

4.3. Effects of K Fertilizer on Forage Quality of Alfalfa

Defining the quality of alfalfa hay precisely remains challenging due to the influence of numerous factors. These include sensory indicators such as physical structure, color, and odor, as well as nutritional parameters like CP, fiber, and energy content. Furthermore, the presence of anti-nutritional factors and the subsequent production performance of livestock must also be considered. Currently, nutritional indices serve as the primary basis for evaluating alfalfa hay quality. Among these, CP, ADF, NDF, TDN, and RFV are regarded as the most critical indicators by dairy producers. CP content serves as a crucial indicator of forage quality, with higher contents indicating increased nutritional value [45]. Fertilizer applications significantly improved alfalfa CP in China regardless of soil P and soil K supply levels [46]. K is a key regulator of enzyme activities involved in photosynthesis and the transport of photosynthates, which provides the carbon skeletons for protein synthesis and likely contributed to the observed numerical increase in CP [2]. Furthermore, K is essential for efficient nitrogen fixation in alfalfa, enhancing nitrogen availability for CP production. Our study’s results align with this finding, as increased K application substantially augmented the CP. Notably, the highest CP content was observed with the 200 kg ha−1 treatment in 2024. TDN is one of the important parameters for evaluating the nutritional value of feed. The calculation of TDN comprehensively considers the digestibility and energy contributions of nutrients such as protein, fat, and carbohydrates in the feed. Therefore, it can more accurately reflect the impact of feed on animal growth and productive performance. In our study, application of K fertilizer has led to varying degrees of increase in the TDN of alfalfa, with a more pronounced effect observed in 2024. The most pronounced effect was the decline in fiber fractions, as K promotes cell elongation, thereby diluting the relative concentration of cell wall components like ADF and NDF [47,48]. Our study revealed that the ADF and NDF contents exhibited an initial decreased as K fertilizer application rates increased. Notably, both ADF and NDF exhibited a marked decline in 2024. That was not along with the findings of Wan et al. [47], this discrepancy in results may be attributed to the initially low K concentration at the experimental site.
The Relative Feeding Value (RFV) is an index increasingly used in recent years to evaluate and compare forage quality based on ADF and NDF values, and it serves as a predictive measure for both forage intake and energy value in pastures, making it an essential tool in assessing forage quality [45]. A higher RFV corresponds to better overall nutritional value and superior forage quality. In our study, the RFV showed a substantial increase, exceeding 170 at application rates above 200 kg ha−1. The stronger response in 2024 suggests that soil potassium depletion might occur over time, making fertilization increasingly necessary to maintain peak forage quality.
The inter-annual variability in the response of forage quality parameters to potassium (K) fertilization, as observed between 2023 and 2024, can be attributed to contrasting climatic conditions, particularly precipitation. Adequate moisture in 2024 probably enhanced K mobility and uptake, facilitating its role in nitrogen assimilation and carbohydrate metabolism, thereby significantly improving CP, TDN, and RFV [48]. In contrast, potential water stress in 2023 may have limited K efficacy, resulting in non-significant trends. Furthermore, depletion of the soil’s native K reserve from the first to the second year could have increased crop responsiveness to applied fertilizer in 2024 [49]. The increasing physiological demand of the establishing perennial crop also contributes to the differential response between years.

5. Conclusions

Proper application of K fertilizer can improve the productivity and forage quality of alfalfa. The application of K fertilizer influenced alfalfa forage yield by modulating yield components such as plant density, and plant height, especially the mass shoot−1. In terms of quality, K fertilization led to improved nutritive value, reflected by increased CP and TDN, as well as decreased ADF and NDF. This synergistic effect culminated in a RFV surpassing 170 at application rates above 200 kg ha−1, meeting the standard for high-quality forage. Comprehensively considering both yield and quality under such conditions, a K fertilizer application rate of 273.2 kg ha−1 of K2O is suggested as a suitable reference. Future research should incorporate comprehensive nutrient monitoring to elucidate the underlying processes and validate these findings across diverse growing environments.

Supplementary Materials

The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/agronomy15102328/s1, Table S1: Effects of factors and their interactions on forage yield and yield-components traits; Table S2: Effects of year, K and their interaction on forage quality traits.

Author Contributions

Methodology, Y.W. and L.Y.; formal analysis, Y.W.; investigation, L.C., S.L., W.L.; Z.L., and W.Y.; resources, L.Y.; data curation, Y.W.; writing—original draft preparation, Y.W.; writing—review and editing, Y.W. and L.Y.; funding acquisition, Y.W. and L.Y. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by “Inner Mongolia Department of Education First-Class Discipline Research Special Project, grant number YLXKZX-NND-037”, “2023 Research Start-up Fund for the Introduction of High-Level and Outstanding Doctoral Talents, grant number NDYB2023-44”, “Hohhot Science and Technology Innovation Talent Project, grant number 2023RC-Institute-232”, “Major Innovation Platform Construction Project of the National Grassland Technology Innovation Center (Preparation), grant number CCPTZX2024BS02-3-2”, “Inner Mongolia Autonomous Region Science and Technology Program Project, grant number 2023YFHH0083” and “Capacity Building Project of Technology Engineering Center of Drought and Cold-Resistant Grass Breeding in North of the National Forestry and Grassland Administration, China, grant number BR221029 and BR251016”.

Data Availability Statement

The original contributions presented in this study are included in this article/Supplementary Materials. Further inquiries can be directed to the corresponding author.

Conflicts of Interest

The authors declare no conflicts of interest. The funders had no role in the design of this study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.

References

  1. Feng, X.; Wang, Y.; Zhang, N.; Wu, Z.; Zeng, Q.; Wu, J.; Wu, X.; Wang, L.; Zhang, J.; Qi, Y. Genome-wide systematic characterization of the HAK/KUP/KT gene family and its expression profile during plant growth and in response to low-K+ stress in Saccharum. BMC Plant Biol. 2020, 20, 20. [Google Scholar] [CrossRef]
  2. Jungers, J.M.; Kaiser, D.E.; Lamb, J.F.S.; Lamb, J.A.; Noland, R.L.; Samac, D.A.; Wells, M.S.; Sheaffer, C.C. Potassium fertilization affects alfalfa forage yield, nutritive value, root traits, and persistence. Agron. J. 2019, 111, 2843–2852. [Google Scholar] [CrossRef]
  3. Prabhu, A.S.; Fageria, N.K.; Huber, D.M.; Rodrigues, F.A. Potassium and plant disease. In Mineral Nutrition and Plant Disease; Datnoff, L.E., Elmer, W.H., Huber, D.M., Eds.; American Phytopathological Society Press: Saint Paul, MN, USA, 2007; pp. 57–58. [Google Scholar]
  4. Wang, M.; Zheng, Q.; Shen, Q.; Guo, S. The critical role of potassium in plant stress response. Int. J. Mol. Sci. 2013, 14, 7370–7390. [Google Scholar] [CrossRef]
  5. Institute of Soil and Fertilizer, Chinese Academy of Agricultural Science. China Chemical Fertilizer and Regionalization; China Agricultural Science and Technology Press: Beijing, China, 1986. [Google Scholar]
  6. Luo, X. Wheat Genotypes Tolerance Identification to Low Potassium Stress at Seeding Stage and Genome-Wide Association Analysis of Low Potassium Tolerance Related Traits. Master’s Thesis, Henan Agricultural University, Zhengzhou, China, 2020. [Google Scholar]
  7. He, F.; Han, D.; Wan, L.; Li, X. The nutrient situations in the major alfalfa producing areas of China. J. Plant Nutr. Fertil. 2014, 20, 503–509. [Google Scholar]
  8. Lanyon, L.E.; Smith, F.W. Potassium nutrition of alfalfa and other forage legumes: Temperate and tropical. In Potassium in Agriculture; Munson, R.D., Ed.; ASA: Madison, WI, USA, 1985. [Google Scholar]
  9. Dale, S. Effects of potassium topdressing a low fertility silt loam soil on alfalfa herbage yields and composition and on soil K values. Agron. J. 1975, 67, 60–64. [Google Scholar] [CrossRef]
  10. Collins, M.; Lang, D.J.; Kelling, K.A. Effects of phosphorus, potassium, and sulfur on alfalfa nitrogen-fixation under field conditions. Agron. J. 1986, 78, 959–963. [Google Scholar] [CrossRef]
  11. Berg, W.K.; Cunningham, S.M.; Brouder, S.M.; Joern, B.C.; Johnson, K.D.; Santini, J.B.; Volenec, J.J. The long-term impact of phosphorus and potassium fertilization on alfalfa yield and yield components. Crop Sci. 2007, 47, 2198–2209. [Google Scholar] [CrossRef]
  12. Berg, W.K.; Cunningham, S.M.; Brouder, S.M.; Joern, B.C.; Johnson, K.D.; Santini, J.B.; Volenec, J.J. Influence of phosphorus and potassium on alfalfa yield and yield components. Crop Sci. 2005, 45, 297–304. [Google Scholar] [CrossRef]
  13. Macolino, S.; Lauriault, L.M.; Rimi, F.; Ziliotto, U. Phosphorus and potassium fertilizer effects on alfalfa and soil in a non-limited soil. Agron. J. 2013, 105, 1613–1618. [Google Scholar] [CrossRef]
  14. Thinguldstad, B.; Tucker1, J.J.; Baxter, L.; Segers, J.R. Impact of potassium application and harvest regime in alfalfa yield, forage quality and stand persistence. J. Anim. Sci. 2019, 97, 15. [Google Scholar] [CrossRef]
  15. Fan, F.; Xu, S.; Zhang, Q.; He, F.; Hou, M.; Song, X. Study on relativity between alfalfa’s yields and nutrition constituent effect of nitrogen, phosphorus and potassium fertilizer. Chin. Soil Fertil. 2011, 2, 51–56. [Google Scholar]
  16. Cao, S.; He, Y.; Zhang, L.; Chen, Y.; Yang, W.; Yao, S.; Sun, Q. Spatiotemporal characteristics of drought and its impact on vegetation in the vegetation region of Northwest China. Ecol. Indic. 2021, 133, 108420. [Google Scholar] [CrossRef]
  17. Wei, Y.; Zhu, L.; Chen, Y.; Cao, X.; Yu, H. Spatiotemporal variations in drought and vegetation response in Inner Mongolia from 1982 to 2019. Remote Sens. 2022, 14, 3803. [Google Scholar] [CrossRef]
  18. de Holanda, S.F.; Vargas, L.K.; Granada, C.E. Challenges for sustainable production in sandy soils: A review. Environ. Dev. Sustain. 2025, 27, 53–66. [Google Scholar] [CrossRef]
  19. Musei, S.K.; Kuyah, S.; Nyawira, S.; Ng’ang’a, S.K.; Karugu, W.N.; Smucker, A.; Nkurunziza, L. Sandy soil reclamation technologiesto improve crop productivity and soilhealth: A review. Front. Soil Sci. 2024, 4, 1345895. [Google Scholar] [CrossRef]
  20. Liu, X.; Lv, X.; Xu, Z.; Yang, X. Effects of mechanical compaction on rhizosphere soil properties andbacterial diversity in maize field headlands. Transactions of the Chinese Society of Agricultural Engineering 2025, GB41, 117–126. [Google Scholar]
  21. Wang, Y.; Zhang, J.; Yu, L.; Xu, Z.; Samac, D.A. Overwintering and yield responses of two late-summer seeded alfalfa cultivars to phosphate supply. Agronomy 2022, 12, 327. [Google Scholar] [CrossRef]
  22. Wang, C.; Ma, B.L.; Yan, X.; Han, J.; Guo, Y.; Wang, Y.; Li, P. Yields of alfalfa varieties with different fall-dormancy levels in a temperate environment. Agron. J. 2009, 101, 1146–1152. [Google Scholar] [CrossRef]
  23. Yang, H.H. Effects of Nitrogen, Phosporus and potassium fertilizers on yield and quality of alfalfa under drip irrigation. Master’s Thesis, Tarim University, Alaer, China, 2017. [Google Scholar]
  24. Barbarick, K.A. Potassium fertilization of alfalfa grown on a soil high in potassium. Agron. J. 1985, 77, 442–445. [Google Scholar] [CrossRef]
  25. Burmester, C.H.; Mullins, G.L.; Ball, D.M. Potassium fertilization effects on yield and longevity of established alfalfa. Commun. Soil Sci. Plant Anal. 2008, 22, 2047–2062. [Google Scholar] [CrossRef]
  26. Ma, N.; Li, Y.; Su, S.; Ma, P.; Han, Y.; Meng, J.; Fu, W.; Qin, T. Effects of nitrogen, phosphorus and potassium ratio fertilizer on the yield and quality of Medicago sativa cv. Beilin 202. Grassl. Turf 2008, 38, 48–54. [Google Scholar]
  27. Yang, H.; Cao, M.; Li, C.; Li, F. Effects of superphosphate and potassium chloride fertilization on alfalfa. Pratacultural Sci. 2003, 20, 19–22. [Google Scholar]
  28. Kang, G.-l. Effect of different potassium fertilizer on the yield and quality of alfalfa. Tianjin Agric. Sci. 2014, 20, 81–82. [Google Scholar]
  29. Xiao, X.H. Effects of different ratio of nitrogen, phosphorus and potassium fertilizer on yield, quality and root nodule bacteria number of alfalfa (Medicago sativa L.). Master’s thesis, Xinjiang Agriculture University, Urumchi, China, 2016. [Google Scholar]
  30. Etesami, H.; Beattie, G.A. Mining halophytes for plant growth-promoting halotolerant bacteria to enhance the salinity tolerance of non-halophytic crops. Front. Microbiol. 2018, 9, 317452. [Google Scholar] [CrossRef] [PubMed]
  31. Oh, D.-H.; Hong, H.; Lee, S.Y.; Yun, D.-J.; Bohnert, H.J.; Dassanayake, M. Genome structures and transcriptomes signify niche adaptation for the multiple-Ion-tolerant extremophyte Schrenkiella parvula. Plant Physiol. 2014, 164, 2123–2138. [Google Scholar] [CrossRef]
  32. Chen, S.; Tang, Y.; Zhang, B.; Liu, H.; Xiong, F.; Xu, K.; Wei, W.; You, Q.; Lu, M.; Shi, L. Effects of potassium fertilizer rates on biomass, yield and nutrients absorption and utilization of oilseed rape in the middle reaches of the Yangtze River. Chin. J. Oil Crop Sci. 2023, 12, 312–323. [Google Scholar]
  33. Hong, F. Alfalfa Science; China Agricultural Press: Bejing, China, 2009. [Google Scholar]
  34. Volenec, J.J.; Cherney, J.H.; Johnson, K.D. Yield components, plant morphology, and forage quality of alfalfa as influenced by plant population. Crop Sci. 1987, 27, 321–326. [Google Scholar] [CrossRef]
  35. Stout, D.G.; Acharya, S.N.; Huang, H.C.; Hanna, M.R. Alfalfa plant death during the summer versus the winter in interior British Columbia. Can. J. Plant Sci. 1992, 72, 931–936. [Google Scholar] [CrossRef]
  36. Lemaire, G.; Onillon, B.; Gosse, G.; Chartier, M.; Allirand, J.M. Nitrogen distribution within a lucerne canopy during regrowth: Relation with light distribution. Ann. Bot. 1991, 68, 483–488. [Google Scholar] [CrossRef]
  37. Simons, R.G.; Grant, C.A. Effect of fertilizer placement on yield of established alfalfa stands. Can. J. Plantence 1995, 75, 883–887. [Google Scholar] [CrossRef]
  38. Hanson, R.G.; Macgregor, J.M. Soil and alfalfa plant characteristics as affected by a decade of fertilization. Agron. J. 1966, 58, 3–5. [Google Scholar] [CrossRef]
  39. White, J.; Harper, J.L. Correlated changes in plant size and number in plant populations. J. Ecol. 1970, 58, 467–485. [Google Scholar] [CrossRef]
  40. Suzuki, M. Effects of stand age on agronomic, morphological and chemical characteristics of alfalfa. Can. J. Plant Sci. 1991, 71, 445–452. [Google Scholar] [CrossRef]
  41. Frakes, R.V.; Davis, R.L.; Patterson, F.L. The breeding behavior of yield and related variables in alfalfa: II. Associations between characters. Crop Sci. 1961, 1, 207–209. [Google Scholar] [CrossRef]
  42. Cooper, R.B.; Blaser, R.E.; Brown, R.H. Potassium nutrition effects on net photosynthesis and morphology of alfalfa. Soil Sci. Soc. Am. J. 1967, 31, 231. [Google Scholar] [CrossRef]
  43. Ventroni, L.M.; Volenec, J.J.; Cangiano, C.A. Fall dormancy and cutting frequency impact on alfalfa yield and yield components. Field Crops Res. 2010, 119, 252–259. [Google Scholar] [CrossRef]
  44. Li, R.; Volenec, J.J.; Joern, B.C.; Cunningham, S.M. Potassium and nitrogen effects on carbohydrate and protein metabolism in alfalfa roots. J. Plant Nutr. 1997, 20, 511–529. [Google Scholar] [CrossRef]
  45. Liu, J.; Lu, F.; Zhu, Y.; Wu, H.; Ahmad, I.; Dong, G.; Zhou, G.; Wu, Y. The Effects of planting density and nitrogen application on the growth quality of alfalfa forage in saline soils. Agriculture 2024, 14, 302. [Google Scholar] [CrossRef]
  46. Kamran, M.; Yan, Z.A.; Jia, Q.M.; Chang, S.H.; Ahmad, I.; Ghani, M.U.; Hou, F.J. Irrigation and nitrogen fertilization influence on alfalfa yield, nutritive value, and resource use efficiency in an arid environment. Field Crops Res. 2022, 284, 108587. [Google Scholar] [CrossRef]
  47. Wan, W.; Li, Y.; Li, H. Yield and quality of alfalfa (Medicago sativa L.) in response to fertilizer application in China: A meta-analysis. Front. Plant Sci. 2022, 13, 1051725. [Google Scholar] [CrossRef]
  48. Öborn, I.; Andrist-Rangel, Y.; Askekaard, M.; Grant, C.A.; Watson, C.A.; Edwards, A.C. Critical aspects of potassium management in agricultural systems. Soil Use Manag. 2005, 21, 102–112. [Google Scholar] [CrossRef]
  49. Romheld, V.; Kirkby, E. Research on potassium in agriculture: Needs and prospects. Plant Soil 2010, 335, 155–180. [Google Scholar] [CrossRef]
Agronomy 15 02328 g001
Figure 1. Regression equations for estimating the K fertilizer application rates on the average cumulative productivity of three harvests over two years.
Figure 1. Regression equations for estimating the K fertilizer application rates on the average cumulative productivity of three harvests over two years.
Agronomy 15 02328 g001
Agronomy 15 02328 g002
Figure 2. Plant density of alfalfa under different K fertilizer rates in two years. Each bar represents the average of 3 data. The error bars represent the standard deviation of the mean. H1, H2, and H3 refer to the first, second, and third harvest, respectively. Different lowercase letters indicate significant differences in plant density among different K application rates at the same harvest period (p < 0.05).
Figure 2. Plant density of alfalfa under different K fertilizer rates in two years. Each bar represents the average of 3 data. The error bars represent the standard deviation of the mean. H1, H2, and H3 refer to the first, second, and third harvest, respectively. Different lowercase letters indicate significant differences in plant density among different K application rates at the same harvest period (p < 0.05).
Agronomy 15 02328 g002
Agronomy 15 02328 g003
Figure 3. Shoot density of alfalfa under different K fertilizer rates in two years. The point in each subfigure was the average of 3 data. Error bars represent the standard error of the mean. H1, H2, and H3 refer to the first, second, and third harvest, respectively. Different lowercase letters indicate significant differences in shoot density among different K application rates at the same harvest period (p < 0.05).
Figure 3. Shoot density of alfalfa under different K fertilizer rates in two years. The point in each subfigure was the average of 3 data. Error bars represent the standard error of the mean. H1, H2, and H3 refer to the first, second, and third harvest, respectively. Different lowercase letters indicate significant differences in shoot density among different K application rates at the same harvest period (p < 0.05).
Agronomy 15 02328 g003
Agronomy 15 02328 g004
Figure 4. Shoot mass of alfalfa under different K fertilizer rates in two years. The point in each subfigure was the average of 3 data. Error bars represent the standard error of the mean. H1, H2, and H3 refer to the first, second, and third harvest, respectively. Different lowercase letters indicate significant differences in shoot mass among different K application rates at the same harvest period (p < 0.05).
Figure 4. Shoot mass of alfalfa under different K fertilizer rates in two years. The point in each subfigure was the average of 3 data. Error bars represent the standard error of the mean. H1, H2, and H3 refer to the first, second, and third harvest, respectively. Different lowercase letters indicate significant differences in shoot mass among different K application rates at the same harvest period (p < 0.05).
Agronomy 15 02328 g004
Agronomy 15 02328 g005
Figure 5. Plant height of alfalfa under different K fertilizer rates in two years. The point in each subfigure was the average of 3 data. Error bars represent the standard error of the mean. H1, H2, and H3 refer to the first, second, and third harvest, respectively. Different lowercase letters indicate significant differences in plant height among different K application rates at the same harvest period (p < 0.05).
Figure 5. Plant height of alfalfa under different K fertilizer rates in two years. The point in each subfigure was the average of 3 data. Error bars represent the standard error of the mean. H1, H2, and H3 refer to the first, second, and third harvest, respectively. Different lowercase letters indicate significant differences in plant height among different K application rates at the same harvest period (p < 0.05).
Agronomy 15 02328 g005
Agronomy 15 02328 g006
Figure 6. Regression equations for estimating the plants m−2, shoots m−2, mass shoot−1, and height shoot−1 on forage yield of alfalfa.
Figure 6. Regression equations for estimating the plants m−2, shoots m−2, mass shoot−1, and height shoot−1 on forage yield of alfalfa.
Agronomy 15 02328 g006
Table 1. Air temperature and total precipitation (precip.) by month for each year of this study.
Table 1. Air temperature and total precipitation (precip.) by month for each year of this study.
Month202220232024
Temp. (°C)Precip. (mm)Temp. (°C)Precip. (mm)Temp. (°C)Precip. (mm)
January−10.54.4−12.50.1−14.01.2
February−12.04.5−7.53.8−12.55.4
March0.024.40.51.00.02.1
April7.010.34.536.29.552.7
May13.011.712.516.915.012.2
June20.038.918.528.418.036.5
July22.059.020.5127.421.06.9
August19.040.319.50.819.029.2
September14.58.215.041.513.086.3
October4.517.97.510.46.534.8
November−3.017.5−6.50.8−1.02.4
December−13.51.1−12.51.1−14.01.3
Note: the table temperatures were the average high and average low temperatures.
Table 2. Forage yield (kg ha−1) of alfalfa under different K fertilizer application rates in two years.
Table 2. Forage yield (kg ha−1) of alfalfa under different K fertilizer application rates in two years.
Applied K
(kg ha−1 of K2O)		20232024
H1H2H3TotalH1H2H3Total
04728.4 c3971.2 b1364.4 d10,063.7 c4474.2 d3624.6 d2668.5 b10,767.3 c
1005469.8 bc4742.1 b1705.4 cd11,917.4 b5699.7 c4206.4 cd3005.4 b12,911.6 b
2007098.4 a5840.4 a1962.7 bc14,901.3 a7524.5 ab5105.7 bc3626.1 a16,256.4 a
3005828.0 b5933.0 a2393.6 b14,155.7 a8245.5 a5490.4 ab3590.9 a17,326.8 a
4004759.9 c3899.2 b2966.3 a11,625.3 bc6993.5 b6216.2 a3467.1 a16,676.8 a
Mean5576.94877.22078.5 12,532.76587.54928.73271.614,787.8
Note: Different lowercase letters in the same column indicate significant differences in the same harvest period at p < 0.05 level. H1, H2, and H3 refer to the first, second and third harvests, respectively.
Table 3. Forage quality of first harvest of alfalfa under different K fertilizer application rates in two years.
Table 3. Forage quality of first harvest of alfalfa under different K fertilizer application rates in two years.
Applied K (kg ha−1 of K2O)20232024
CP (%)ADF (%)NDF (%)TDN (%)RFVCP (%)ADF (%)NDF (%)TDN (%)RFV
019.63 a30.00 a38.44 a59.93 a159.00 a20.23 c31.90 a39.03 a57.67 b152.67 c
10021.07 a30.10 a37.45 a60.03 a162.67 a20.97 bc30.93 b36.97 b64.15 a163.07 b
20021.30 a28.03 a35.85 a62.04 a174.00 a22.13 a30.60 b34.86 c61.01 ab173.63 a
30021.07 a28.27 a35.66 a63.00 a174.33 a21.77 ab30.13 bc34.89 c61.75 ab174.43 a
40021.13 a28.83 a36.49 a63.21 a169.67 a21.30 b29.40 c35.15 c62.45 ab174.70 a
Note: Different lowercase letters in the same column indicate significant differences between different K fertilization rates (p < 0.05).
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

Wang, Y.; Cui, L.; Liu, S.; Li, W.; Li, Z.; Ye, W.; Yu, L. Productivity and Forage Quality of Alfalfa Response to Potassium Fertilizer: A Field Study in Inner Mongolian Plateau. Agronomy 2025, 15, 2328. https://doi.org/10.3390/agronomy15102328

AMA Style

Wang Y, Cui L, Liu S, Li W, Li Z, Ye W, Yu L. Productivity and Forage Quality of Alfalfa Response to Potassium Fertilizer: A Field Study in Inner Mongolian Plateau. Agronomy. 2025; 15(10):2328. https://doi.org/10.3390/agronomy15102328

Chicago/Turabian Style

Wang, Yuntao, Lele Cui, Shenghao Liu, Wenxuan Li, Zhenyi Li, Wenxing Ye, and Linqing Yu. 2025. "Productivity and Forage Quality of Alfalfa Response to Potassium Fertilizer: A Field Study in Inner Mongolian Plateau" Agronomy 15, no. 10: 2328. https://doi.org/10.3390/agronomy15102328

APA Style

Wang, Y., Cui, L., Liu, S., Li, W., Li, Z., Ye, W., & Yu, L. (2025). Productivity and Forage Quality of Alfalfa Response to Potassium Fertilizer: A Field Study in Inner Mongolian Plateau. Agronomy, 15(10), 2328. https://doi.org/10.3390/agronomy15102328

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop