The Impact of Integrated Nutrient Management on Trifolium alexandrinum Varietal Performance in the Indo-Gangetic Plains: A Comparative Yield and Economic Analysis

The importance of selecting an appropriate berseem variety and implementing effective nutrient management practices is crucial for maximizing both the production and economic potential of forage crops. This was clearly demonstrated in a field experiment conducted during the rabi seasons of 2019–2020 and 2020–2021. The experimental setup was a factorial randomized block design incorporating five berseem varieties (Mescavi, HB-1, HB-2, BL-10, and BL-42) and five integrated nutrient management practices: 100% recommended dose of fertilizers (RDF) or NM-1, 75% RDF + plant growth-promoting rhizobacteria (PGPR) or NM-2, 75% RDF + municipal solid waste compost (MSWC) or NM-3, 75% RDF + farmyard manure (FYM) + PGPR or NM-4, and 50% RDF + MSWC + PGPR or NM-5. The objective of the experiment was to evaluate the physio-morphological responses, biomass yield, and economic efficiencies of different berseem varieties under various nutrient management practices. The experimental results highlighted the superior performance of the BL-42 variety in terms of growth and yield attributes compared to the other tested berseem varieties. Specifically, BL-42 showed an enhancement in total green fodder yield by 17.10%, 26.60%, 37.75%, and 28.04% over the varieties BL-10, HB-2, HB-1, and Mescavi, respectively. Moreover, the application of the 75% RDF + FYM + PGPR treatment (NM-4) significantly boosted the total green fodder yield by 13.08%, 14.29%, 34.48%, and 39.02% over the 75% RDF + MSWC, 100% RDF, 75% RDF + PGPR, and 50% RDF + MSWC + PGPR treatments, respectively. In terms of economic returns, BL-42 achieved a significantly higher gross return (GR) and net return (NR) of 194,989 ₹/ha and 145,142 ₹/ha, respectively, compared to the GR and NR of BL-10 (166,512 and 116,665 ₹/ha, respectively). Similarly, the nutrient management practice of 75% RDF + FYM + PGPR recorded the highest GR and NR (191,638 and 137,346 ₹/ha, respectively) compared to the 100% RDF treatment (167,593 and 120,716 ₹/ha, respectively). These findings underscore the critical role of variety selection and tailored nutrient management in optimizing both the yield and economic gains in forage crop cultivation. The significant differences in production and returns highlight the potential of targeted agronomic strategies to enhance the profitability and sustainability of forage farming.

Keywords: berseem; green fodder yield; leaf area index; integrated nutrient management; municipal solid waste compost

The genus Trifolium, belonging to the Leguminosae family, comprises approximately 240 species, with White clover (T. repens), Red clover (T. pratense L.), Alsike clover (T. hybridum L.), and Egyptian clover (T. alexandrinum L.) being the most prominent [[1]]. The term "berseem" has its roots in Arabic and Coptic, with its cultivation in Egypt dating back to 6000 BC [[2]]. This crop is distinguished by its ability to undergo multiple harvests, providing an extended availability of green fodder. It is characterized by high yields and is renowned for its superior quality, particularly in terms of palatability and digestibility, which renders it an invaluable component in animal nutrition [[3]]. On the dry weight basis, the average nutritional content in berseem is 10–12% dry matter, 18–20% crude protein, 2–4% ether extract, 20–23% crude fiber, 50–55% neutral detergent fiber, 30–35% acid detergent fiber, and 8–10% ash content [[4]]. Furthermore, this crop is an efficient nitrogen-fixing legume, contributing approximately 33 to 66 kg of nitrogen per hectare, thereby enhancing the fertility of the soil for subsequent crop cultivation [[5]]. Berseem is widely cultivated in various countries, including India, Egypt, Pakistan, Turkey, and Mediterranean regions, primarily as an annual winter crop [[6]]. India, in particular, leads in the cultivation of this essential forage legume, with an extensive area of 2 million hectares, surpassing even Egypt's significant cultivation of 1.1 million hectares [[7]]. The continuous and enhanced productivity of berseem is vital for augmenting milk production in India, particularly in light of the green fodder shortage that contributes to comparatively lower milk yields. In India, the average milk yield per lactation stands at approximately 1000 kg, which is markedly lower than that observed in European countries, where the average yield per lactation reaches approximately 4252 kg. This discrepancy underscores the importance of berseem in addressing fodder deficit and improving dairy productivity [[8]].

Attaining the optimal yield of berseem remains a considerable challenge in India, primarily due to the suboptimal application of fertilizers and compost in forage crops. Notably, when an adequate amount of fertilizer is applied to berseem, a marked increase in the yield is observed. This is particularly noteworthy given berseem's classification as a legume, which typically requires less nitrogen due to its nitrogen-fixing capabilities. However, empirical evidence indicates that nitrogen application at varying rates, ranging from 30 kg ha−1 to 70 kg ha−1, has significantly enhanced both the fresh and dry matter yield of berseem. This suggests that even leguminous crops like berseem can substantially benefit from tailored nitrogen supplementation, challenging traditional assumptions about their fertilizer requirements [[9]]. Research has emphatically demonstrated that elevated phosphorus levels contribute to significant enhancements in various growth parameters and the nutrient dynamics of plants. Specifically, increased phosphorus availability is correlated with substantial increases in the dry mass of both shoots and roots, as well as the elongation of root structures. Additionally, there is a notable increase in phosphorus accumulation within these plant components. These physiological improvements are not confined to the vegetative aspects alone; they extend to an augmented overall yield. This body of evidence underscores the pivotal role of phosphorus in optimizing plant growth and productivity, highlighting its integral contribution to both structural and metabolic functions in plants [[11]]. The application of 40 kg K2O hectare−1, in conjunction with 2 kg boron hectare−1, has been shown to significantly enhance both green fodder and dry matter yield, as reported in the study [[13]]. Furthermore, research from Egypt, as documented in one study [[14]], indicates that potassium application also leads to notable increases in plant height, leaf count, and fresh weight. However, it is important to note that the efficacy of chemical fertilizers can be further augmented through the integration of organic sources such as compost and biofertilizers. This synergistic approach not only boosts crop productivity but also steers the agricultural system towards greater sustainability, as highlighted in another study [[15]]. In India, farmyard manure (FYM) is the predominant organic source utilized in agriculture; however, its availability falls short of meeting the entire demand for organic inputs. Consequently, there is a pressing need to explore alternative sources of compost. One such potential and largely untapped resource is municipal solid waste compost. This form of compost presents a viable solution to the shortfall of organic material, turning a waste product into a valuable agricultural input. By harnessing municipal solid waste for composting, not only can the gap in organic source requirements be bridged, but it also offers an environmentally sustainable method of waste management [[16], [18]]. Nutritionally, municipal solid waste compost (MSWC) often matches or exceeds farmyard manure in micronutrients [[19]]. However, its variable heavy metal content, based on the source location, is a concern. If tests show low or no heavy metals, MSWC can be safe for use. Utilizing municipal solid waste compost (MSWC) as a substitute for farmyard manure, alongside chemical and biofertilizers, could effectively boost berseem yields. This integrated approach combines the benefits of various fertilizers, enhancing nutrient availability and promoting sustainable agriculture.

The strategic selection of berseem varieties, tailored to specific agro-climatic zones and local environmental conditions, is a critical factor in optimizing yield [[20]]. When this is synergistically combined with precise nutrient management practices, it can markedly elevate berseem productivity. This methodical approach addresses the deficit in green fodder supply, thereby contributing to an increase in milk yield. This highlights the interconnectedness of varietal selection, nutrient management, and dairy productivity within the agricultural ecosystem. The experiment was designed to identify the most suitable variety of berseem, along with the optimal integrated nutrient management practice, specifically for the Indo-Gangetic plains of India. This research aimed to tailor both the crop variety and nutrient strategies to the unique environmental and soil conditions of this region, thereby maximizing agricultural productivity and efficiency.

This investigation was conducted over two consecutive rabi (winter) seasons during 2019–2020 and 2020–2021 at the Agronomy Research Farm of the ICAR-National Dairy Research Institute, situated in Karnal, Haryana, India. Geographically, the farm is positioned at 29°45′ north latitude and 76°58′ east longitude at an elevation of 245 m above mean sea level (MSL). The local climate is predominantly sub-tropical and sub-humid, characterized by sweltering summers. Climatically, Karnal experiences a semi-arid, sub-tropical milieu marked by extreme temperature fluctuations. The hottest months, May and June, exhibit average temperatures ranging from 41 °C to 45 °C. Conversely, the coldest months, December and January, record mean minimum temperatures fluctuating between 1.9 °C and 5 °C, with frost being a frequent occurrence during this period.

Temperature metrics, both maximum and minimum, exhibit an upward trend commencing in early February and persisting until June. The annual precipitation at the experimental site is approximately 690–720 mm, with a substantial 70% accruing during the monsoon months of July to September, while the remainder is distributed across the winter and spring. The bulk of the annual rainfall is primarily confined to the monsoon period, supplemented by occasional cyclonic showers in the winter and spring. The site's mean annual evaporation is recorded at approximately 1520.3 mm, with the daily pan evaporation rates peaking at 10.9 mm in June and dipping to a minimal 1.5 mm in January. The evapotranspiration rate mirrors the temperature pattern throughout the crop cycle. The relative humidity escalates from June through to September.

The meteorological observatory of the ICAR-CSSRI, Karnal, meticulously recorded and compiled the average weekly meteorological data for the standard weeks during the cropping seasons of 2019–2020 and 2020–2021, which is depicted in Figure 1.

The initial physicochemical properties of the experimental site can be seen in Table 1. The study was structured as a factorial randomized block design, incorporating three replications. It encompassed a total of 25 treatment combinations, bifurcated into two distinct factors: berseem varieties and integrated nutrient management strategies. These were further subdivided into five tiers each, with specifics delineated in Table 2. The cultivation of berseem was conducted in a sequential cropping pattern, followed by kharif (rainy season) fodder maize across both years in which the residual impact of the treatments applied in berseem was assessed.

For the berseem crops, the recommended dose of nitrogen, phosphorus, and potassium (RDNPK) was set at 20-60-40 kg ha−1. This nutrient application was facilitated through the use of urea (46% N), single super phosphate (SSP, 16% P2O5), and muriate of potash (60% K2O), all applied as a basal dose during the sowing stage. Plant growth-promoting rhizobacteria (PGPR), comprising nitrogen fixers (NFs), phosphorus solubilizing bacteria (PSB), and potassium solubilizing bacteria (KSB), was applied as a seed treatment at a rate of 6 mL kg−1 of berseem seed, as outlined in the treatment plan. Additionally, well-decomposed municipal solid waste compost (MSWC) and farmyard manure (FYM) were applied at a rate of 10 tonnes hectare−1 during tillage, before sowing berseem, in accordance with the treatment specifications. Before planting, the field designated for the experiment underwent thorough preparation. Initially, cross-harrowing was conducted using a tractor equipped with a disc harrow. This step was followed by a single pass of a rotavator, aimed at enhancing soil tilth. Following these processes, the field was precisely leveled using a wooden plank. Once levelling was completed, the experimental plots were methodically arranged in accordance with a pre-established treatment layout. In the subsequent cultivation of residual fodder maize, half the recommended dose of nitrogen (60 kg ha−1) was applied at the knee stage of growth. The berseem varieties (Mescavi, HB-1, HB-2, BL-10, and BL-42) were sown at a seeding rate of 25 kg ha−1, with sowing dates on 15 October and 13 October for the years 2019 and 2020, respectively.

The harvesting of fodder maize was meticulously conducted upon the attainment of the 50% flowering phase. This process commenced with the strategic removal of plants from the peripheral rows to mitigate any border effect, subsequently followed by the harvest of the central plot area, following the methodology described by [[21]]. The yield of the fresh forage was precisely quantified post-harvest. Subsequently, representative samples of green fodder, weighing approximately 500 g, were subjected to a drying process in a controlled environment, utilizing a hot air oven set at a temperature of 65 ± 5 °C [[22]]. This procedure was continued until a consistent weight was achieved, indicating the removal of moisture. The moisture loss was quantitatively assessed, facilitating the calculation of the dry fodder yield. Following this, the desiccated samples were pulverized to a fine consistency, ensuring they passed through a 40-mesh sieve in a Macro-Wiley mill. This produced a uniform sample, optimal for subsequent chemical analyses.

The harvesting of fodder maize was meticulously conducted upon the attainment of the 50% flowering phase. This process commenced with the strategic removal of plants from the peripheral rows to mitigate any border effect, subsequently followed by the harvest of the central plot area, flowing the methodology described by [[21]]. The yield of the fresh forage was precisely quantified post-harvest. Subsequently, representative samples of green fodder, weighing approximately 500 g, were subjected to a drying process in a controlled environment, utilizing a hot air oven set at a temperature of 65 ± 5 °C [[22]]. This procedure was continued until a consistent weight was achieved, indicating the removal of moisture. The moisture loss was quantitatively assessed, facilitating the calculation of the dry fodder yield. Following this, the desiccated samples were pulverized to a fine consistency, ensuring they passed through a 40-mesh sieve in a Macro-Wiley mill. This produced a uniform sample, optimal for subsequent chemical analyses.

The number of nodules per plant was accurately measured by counting all the nodules on the roots of five specifically chosen plants. Each plant's nodules were carefully inspected and counted. Then, an average of these counts was calculated to represent the average number of nodules per plant. This method provided a precise and accurate evaluation of nodule density in the sampled plants [[5]].

In each plot, five plants were randomly chosen and cut near the ground. Their leaves were then carefully removed and counted. A selection of these leaves was used to determine the leaf area using two methods: a manual graphical technique and a CI-203 laser area meter. The leaf area of all the leaves was estimated by multiplying the area of the sampled leaves by the total leaf count from the five plants, providing an average leaf area per plant. The leaf area index (LAI) was then calculated following the method and formula described by [[23]], which is provided below.

$$\mathrm{L}\mathrm{e}\mathrm{a}\mathrm{f}\mathrm{A}\mathrm{r}\mathrm{e}\mathrm{a}\mathrm{I}\mathrm{n}\mathrm{d}\mathrm{e}\mathrm{x}=\frac{\mathrm{L}\mathrm{e}\mathrm{a}\mathrm{f}\mathrm{A}\mathrm{r}\mathrm{e}\mathrm{a}\mathrm{P}\mathrm{e}\mathrm{r}\mathrm{P}\mathrm{l}\mathrm{a}\mathrm{n}\mathrm{t}({\mathrm{c}\mathrm{m}}^2)}{\mathrm{L}\mathrm{a}\mathrm{n}\mathrm{d}\mathrm{A}\mathrm{r}\mathrm{e}\mathrm{a}\mathrm{P}\mathrm{e}\mathrm{r}\mathrm{P}\mathrm{l}\mathrm{a}\mathrm{n}\mathrm{t}({\mathrm{c}\mathrm{m}}^2)}$$

The economic analysis solely focused on the variable production costs. These costs included human labor, machinery use (such as tractors, plows, planters, etc.), input expenses (seeds, fertilizers, and pesticides), and costs for harvesting and threshing. The value of the land was not included in the production cost. Costs for different farming activities during crop growth were calculated separately for each item. The total cost was determined by summing up the expenses for all operations according to each treatment on a per-hectare basis, expressed in ₹/ha. The gross returns per hectare were calculated by multiplying the total yield of fodder or straw with the current market prices of berseem and fodder maize. The net returns were calculated by subtracting the total cultivation cost from the gross returns for each treatment. The benefit–cost ratio (BCR) was determined by dividing the net returns by the cultivation cost for different treatments. The economic efficiency was calculated by considering the yield and gross return in relation to the duration of the crop growth, the formula of which is given below:

Net Returns = Gross returns ((₹/ha) − Total cost of cultivation (₹/ha)

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

The returns per rupee invested (RPRI) was calculating using the following:

$$\mathrm{R}\mathrm{P}\mathrm{R}\mathrm{P}(\mathrm{₹}/\mathrm{h}\mathrm{a})=\frac{\mathrm{G}\mathrm{r}\mathrm{o}\mathrm{s}\mathrm{s}\mathrm{r}\mathrm{e}\mathrm{t}\mathrm{u}\mathrm{r}\mathrm{n}\mathrm{s}(\mathrm{₹}/\mathrm{h}\mathrm{a})}{\mathrm{T}\mathrm{h}\mathrm{e}\mathrm{t}\mathrm{o}\mathrm{t}\mathrm{a}\mathrm{l}\mathrm{c}\mathrm{o}\mathrm{s}\mathrm{t}\mathrm{o}\mathrm{f}\mathrm{c}\mathrm{u}\mathrm{l}\mathrm{t}\mathrm{i}\mathrm{v}\mathrm{a}\mathrm{t}\mathrm{i}\mathrm{o}\mathrm{n}(\mathrm{₹}/\mathrm{h}\mathrm{a})}$$

$$\mathrm{E}\mathrm{c}\mathrm{o}\mathrm{n}\mathrm{o}\mathrm{m}\mathrm{i}\mathrm{c}\mathrm{e}\mathrm{f}\mathrm{f}\mathrm{i}\mathrm{c}\mathrm{i}\mathrm{e}\mathrm{n}\mathrm{c}\mathrm{y}(\mathrm{₹}/\mathrm{h}\mathrm{a}/\mathrm{d}\mathrm{a}\mathrm{y})=\frac{\mathrm{G}\mathrm{r}\mathrm{o}\mathrm{s}\mathrm{s}\mathrm{r}\mathrm{e}\mathrm{t}\mathrm{u}\mathrm{r}\mathrm{n}\mathrm{s}(\mathrm{₹}/\mathrm{h}\mathrm{a})}{\mathrm{C}\mathrm{r}\mathrm{o}\mathrm{p}\mathrm{d}\mathrm{u}\mathrm{r}\mathrm{a}\mathrm{t}\mathrm{i}\mathrm{o}\mathrm{n}(\mathrm{d}\mathrm{a}\mathrm{y}\mathrm{s})}$$

The data collected for various parameters were analyzed using the analysis of variance (ANOVA) technique, as outlined by Gomez and Gomez in 1984, for a factorial randomized block design. This analysis was performed using SAS 9.1 software from the SAS Institute in Cary, NC, USA. To determine the effects of the treatments, the least significant difference (LSD) test was applied at a 5% significance level (p = 0.05).

The results indicated that out of the factors studied—different years, berseem varieties, and integrated nutrient management (INM) approaches—the latter two significantly affected the plant height of berseem at various cutting stages (Table 3). At 30 days after sowing (DAS) and up to the second cut, the Mescavi variety had the highest plant height (40.41, 81.31, and 82.44 cm, respectively) compared to other tested varieties. However, its performance was poorer in the later stages (third, fourth, and fifth cutting) compared to the HB-2, BL-10, and BL-42 varieties. In contrast, the BL-42 variety showed significantly greater plant heights during the third, fourth, and fifth cuts (81.44, 75.78, and 66.81 cm, respectively), followed by the BL-10 variety at these stages (77.07, 69.59, and 56.13 cm, respectively). Compared to Mescavi, the BL-42 variety exhibited 8.17%, 39.30%, and 58.22% higher plant heights at the third, fourth, and fifth cuts, respectively.

The different INM schemes showed varying effects on the plant heights of berseem varieties. Initially, applying 100% RDF led to the best plant height at the first and second cuts (80.87 and 81.48 cm, respectively), which was comparable to the plants fertilized with 75% RDF in addition to FYM and PGPR (79.72 and 80.07 cm, respectively). However, in the later stages of harvesting (third, fourth, and fifth cuts), the highest plant heights were observed in the treatment with 75% RDF + FYM + PGPR (82.42, 70.35, and 56.89 cm, respectively), surpassing those with 100% RDF application. Specifically, at these later stages, the application of 75% RDF + FYM + PGPR resulted in plant heights that were 3.70%, 5.76%, and 9.30% higher, respectively, compared to 100% RDF.

Conversely, the lowest plant heights at the first, second, and third cuts were observed in the treatment with 50% RDF + municipal solid waste compost (MSWC) + PGPR (67.67, 71.96, and 70.72 cm, respectively). In the fourth and fifth cuts, the lowest plant heights were recorded in the treatment with 75% RDF + PGPR (61.22 and 47.96 cm, respectively) when compared to the other tested nutrient management practices.

The quantity of leaves is crucial for the herbage yield of different fodder crops, affecting their nutritional value and palatability. The data indicates that the number of leaves can be influenced by the variety of the crop and the nutrient management practices that are employed. According to the pooled data presented in Table 4, the number of leaves per plant was significantly affected by different berseem varieties and the combined use of organic and inorganic nutrients. However, the number of leaves was not significantly impacted by the study years.

Regarding the berseem varieties, Mescavi showed a higher number of functional leaves in the initial stages (30, 55, and 85 days after sowing (DAS) with counts of 7.79, 20.76, and 21.31 leaves, respectively). At later stages, the BL-42 variety had a significantly higher number of leaves during the third, fourth, and fifth cuts (22.14, 21.64, and 15.47 leaves, respectively) compared to the other varieties. In contrast, the HB-1 variety showed fewer leaves, similar to HB-2, when compared to the other tested berseem varieties.

In terms of nutrient management, the treatment with 75% RDF + FYM + PGPR resulted in a higher number of functional leaves across all stages (first cut: 19.62, second cut: 21.76, third cut: 23.72, fourth cut: 21.19, and fifth cut: 14.85). This was followed by the treatment with 100% RDF, which showed 18.89 and 21.37 leaves at the first and second cuts, respectively. In the later stages, the treatment with 75% RDF + FYM + PGPR significantly increased the number of trifoliate leaves by 9.54%, 18.27%, and 22.11% over the 100% RDF treatment at the third, fourth, and fifth cuts, respectively. Conversely, the lowest number of leaves was observed in the treatment with 50% RDF + MSWC + PGPR across all stages (first cut: 14.60, second cut: 16.50, third cut: 18.06, fourth cut: 16.21, and fifth cut: 10.04 leaves).

The leaf area index (LAI) is a key indicator of a plant's ability to capture sunlight for photosynthesis, impacting the yield of fodder crops. The LAI of berseem varieties was not significantly influenced by the study years. A detailed outcome of the mean data presented in Table 5 shows a noticeable increase in the LAI due to different berseem varieties and integrated nutrient management practices. Among the berseem varieties, Mescavi showed a significantly higher LAI in the early stages (30 DAS: 0.63, first cut: 0.79, second cut: 0.93). Conversely, BL-42 had a significantly higher LAI in the later stages (third cut: 0.86, fourth cut: 0.80, fifth cut: 0.78) compared to all the cuts of HB-1 and HB-2. BL-10 performed better than the other varieties, except BL-42, with LAI values of 0.47 at 30 DAS, 0.63 at the first cut, 0.80 at the second cut, 0.81 at the third cut, 0.75 at the fourth cut, and 0.69 at the fifth cut, showing parity with BL-42. In terms of nutrient management, the highest LAI was recorded in the treatment with 100% RDF in the initial two cuts (0.61 at 30 DAS, 0.77 at the first cut, and 0.95 at the second cut), followed by the treatment with 75% RDF + FYM + PGPR (0.58 at 30 DAS, 0.74 at the first cut, and 0.92 at the second cut), which was statistically on par with 100% RDF. However, in the later stages (third, fourth, and fifth cuts), the 75% RDF + FYM + PGPR treatment showed a significantly higher LAI (0.92, 0.84, and 0.78, respectively) compared to 100% RDF (0.76, 0.71, and 0.66, respectively). The treatment with 75% RDF + MSWC had a maximum LAI of 0.81 in the second cut, significantly higher than the 75% RDF + PGPR (0.64) and 50% RDF + MSWC + PGPR (0.56) treatments.

The data on the root nodules of berseem varieties, as influenced by study years, varieties, and nutrient management, are presented in Table 6. The results indicate that while the study years did not significantly affect the number of root nodules, variations in berseem varieties and nutrient management practices did.

Among the berseem varieties, BL-42 showed the highest number of root nodules per plant across all cuts (first cut: 65.99, second cut: 85.75, third cut: 103.53, fourth cut: 98.29, and fifth cut: 87.53 nodules). BL-10 followed, with higher numbers in the second (77.16), third (95.58), fourth (91.67), and fifth cuts (76.99 nodules). The HB-2 variety had nodules at 30 days after sowing (DAS) (18.26), increasing through the first (54.43), second (71.42), third (93.15), fourth (89.41), to the fifth cut (76.12 nodules). HB-1 had similar numbers, with 18.01 nodules at 30 DAS, and increasing through the first (53.36), second (69.06), third (91.48), fourth (86.35), to the fifth cut (71.13 nodules). BL-42 showed significantly higher nodule numbers than HB-2 and HB-1 at the third cut by 11.14% and 13.16%, respectively. Mescavi, in contrast, had fewer nodules in the third (87.62), fourth (77.89), and fifth cuts (59.83 nodules).

Regarding nutrient management, the treatment with 75% RDF + FYM + PGPR resulted in the highest number of nodules per plant (30 DAS: 25.48, first cut: 66.04, second cut: 82.64, third cut: 101.51, fourth cut: 95.55, and fifth cut: 80.42 nodules). This was followed by the treatment with 75% RDF + PGPR (30 DAS: 22.04, first cut: 62.22, second cut: 75.85, third cut: 94.51, fourth cut: 88.85, and fifth cut: 74.84 nodules). The lowest number of nodules was observed in the treatment with 50% RDF + MSWC + PGPR (30 DAS: 17.66, first cut: 52.41, second cut: 70.27, third cut: 87.59, fourth cut: 81.78, and fifth cut: 67.79 nodules), which was comparable to the 100% RDF treatment at the fourth and fifth cuts. The berseem varieties fertilized with 75% RDF + FYM + PGPR had higher nodule numbers at all cuts (first to fifth cuts: 19.17%, 13.35%, 12.21%, 12.28%, and 13.25% higher, respectively) compared to 100% RDF.

Regarding the various berseem varieties, BL-42 recorded the highest total green fodder production, reaching 97.49 tons per hectare, surpassing BL-10 and HB-2, which produced 83.26 and 77.01 tons per hectare, respectively. BL-42's performance exceeded other varieties by a range of 17.10% to 28.04%. While Mescavi yielded the highest in the initial cuts, BL-42 dominated in the subsequent stages (Table 7).

In terms of nutrient management, the combination of 75% RDF + FYM + PGPR was the most productive, yielding an impressive 95.85 tons per hectare of green fodder. This INM strategy proved to be significantly more effective than the alternatives, including 75% RDF + MSWC, 100% RDF, and the other tested treatments.

As for dry fodder yield, the study year, berseem variety, and nutrient management approach did not show a significant influence. Mescavi led in the initial yield, but BL-42 outperformed it in the later harvests. In total, BL-42 achieved the highest dry fodder production, amounting to 14.42 tons per hectare, markedly surpassing the yields of the other varieties.

When assessing the nutrient management effect on dry fodder yield, the 100% RDF treatment initially led the way, but the 75% RDF combined with FYM and PGPR excelled both in the later cuts and overall. This approach significantly enhanced the yield across all stages, demonstrating its superiority over other nutrient management practices.

The cost of cultivation (CoC) for various berseem varieties was calculated based on the prevailing rates for inputs, labor, and produce during the crop's growing period. According to the data (Table 8), the CoC for berseem was not significantly affected by the variety of berseem or the study years. Additionally, the data showed that among the different nutrient management options, the use of 75% RDF + PGPR and the use of 100% RDF was associated with a lower CoC. In contrast, a higher CoC was observed with the use of 75% RDF combined with FYM and PGPR.

The results indicated that both gross return (GR) and net return (NR) for different varieties of berseem were not significantly affected by the study years, as detailed in Table 7. Among the berseem varieties, BL-42 achieved the highest significant GR and NR, with 194,989 and 145,142 ₹ ha−1, respectively, surpassing the GR and NR of BL-10, which were 166,512 and 116,665 ₹ ha−1, respectively. In contrast, the HB-1 variety showed the lowest GR and NR among the berseem varieties, with 141,549 and 91,702 ₹ ha−1, respectively.

Comparing the different nutrient management options, the application of 75% RDF + FYM + PGPR resulted in the highest GR and NR, amounting to 191,638 and 137,346 ₹ ha−1, respectively. This was significantly higher than the GR and NR obtained with 100% RDF, which were 167,593 and 120,716 ₹ ha−1, respectively. Among all the nutrient management options tested, the treatment with 50% RDF + MSWC + PGPR recorded the lowest GR and NR, significantly lower than the other treatments.

The results indicated that the benefit–cost ratio of different varieties of berseem and various nutrient management approaches did not show significant variation across the study years, as seen in Table 7. Among the berseem varieties, BL-42 exhibited the highest BCR at 2.91, surpassing other varieties such as BL-10 (2.34), Mescavi (2.04), and HB-2 (2.09). The BCRs for Mescavi and HB-2 were not significantly different from the other varieties. The lowest BCR was recorded for the HB-1 variety at 1.84, compared to the other berseem varieties.

In terms of nutrient management approaches, the highest BCR was observed in the treatment with 100% RDF, standing at 2.58, which was statistically on par with the 75% RDF combined with FYM and PGPR at 2.53. The BCR for the 75% RDF combined with MSWC was 2.28, which was significantly higher than that of the 75% RDF combined with PGPR (2.11) and the 50% RDF combined with MSWC and PGPR (1.72).

The data presented in Table 8 showed no significant differences in economic efficiency across different study years. Analyzing the data for various berseem varieties, BL-42 emerged as the most economically efficient, with a significant lead at 1114.22 ₹ha−1 day−1. The Mescavi and HB-2 varieties, with economic efficiencies of 866.88 ₹ ha−1 day−1 and 880.12 ₹ ha−1 day−1, respectively, did not show significant differences compared to the other varieties. The HB-1 variety recorded the lowest economic efficiency at 880.12 ₹ ha−1 day−1 among the different berseem varieties.

In terms of nutrient management approaches, the 75% RDF + FYM + PGPR treatment achieved the highest economic efficiency at 1095.07 ₹ ha−1 day−1. This was higher compared to the treatments with 75% RDF + MSWC and 100% RDF, which had similar economic efficiencies of 967.93 ₹ ha−1 day−1 and 957.67 ₹ ha−1 day−1, respectively. The lowest economic efficiency was observed in the treatment with 50% RDF + MSWC + PGPR, at 786.77 ₹ ha−1 day−1, which was significantly lower than all other nutrient management treatments.

The data presented in Table 9 indicate that the production efficiency and return per rupee invested (RPRI) of the system were not significantly impacted during the study year. Analysis of different berseem varieties revealed that BL-42 exhibited the highest production efficiency and RPRI, with values of 5.58 q ha−1 day−1 and 3.91 ₹ ha−1, respectively, outperforming the other varieties. BL-42 was also the second-most important variety, showing superior production efficiency and RPRI (4.77 q ha−1 day−1 and 3.34 ₹ ha−1) compared to HB-2 (4.41 q ha−1 day−1 and 3.09 ₹ ha−1) and Mescavi (4.37 q ha−1 day−1 and 3.04 ₹ ha−1), though the latter two varieties were statistically similar. The lowest production efficiency and RPRI (4.05 q ha−1 day−1 and 2.84 ₹ ha−1) were observed in the HB-1 variety. Regarding nutrient management strategies, the combination of 75% RDF + FYM + PGPR led to the highest production efficiency (5.42 q ha−1 day−1), significantly exceeding 100% RDF (4.86 q ha−1 day−1) and 75% RDF with MSWC (4.82 q ha−1 day−1). However, the latter two treatments were comparable. The highest RPRI was recorded with 100% RDF (3.58), followed by 75% RDF with FYM and PGPR (3.53), which were statistically similar. The combination of 50% RDF with MSC and PGPR showed the lowest economic efficiency and RPRI (786.77 q ha−1 day−1 and 2.72 ₹ ha−1, respectively) when compared to all the other treatments.

Plant height and the number of leaves, essential measures of vegetative growth, and the number of leaves, which directly correlate with herbage yield and its nutritional value, are influenced by several factors, including the genetic makeup of the crop variety, soil health, nutrient availability, and environmental interactions [[24], [26]].

Regarding the influence of berseem varieties on plant height, the initial advantage of the Mescavi variety in the early growth stages could be attributed to its genetic predisposition for rapid early growth, which is a desirable trait for early forage [[28]]. However, its performance in the later stages of growth (third, fourth, and fifth cuts) was surpassed by other varieties like BL-42. This shift in growth patterns could be explained by the genetic capacity of BL-42 for sustained growth even in the later stages of the plant's lifecycle [[20]]. Genetically, BL-42 might possess traits that enable it to maintain a robust metabolic rate and efficient nutrient utilization during its entire growth period, unlike Mescavi, which seems to invest more in early growth at the expense of later stages [[29]]. This is evident from the significantly greater plant heights recorded for BL-42 in the later cuts, indicating a genetic advantage in prolonged vegetative vigor [[30]].

The impact of different INM approaches on plant height also highlights the importance of nutrient management in crop growth. The initial efficacy of a 100% recommended dose of fertilizers (RDFs) in promoting plant height can be linked to the immediate availability of essential nutrients in chemical fertilizers, which are readily absorbed by the plants, promoting rapid early growth [[31]]. However, the sustained performance of the combination of 75% RDF with farmyard manure (FYM) and plant growth-promoting rhizobacteria (PGPR) in the later stages underscores the benefits of integrating organic and biological amendments [[31], [33]]. This combination likely improves soil health over time, enhancing its structure, water-holding capacity, and microbial activity, which are crucial for sustained nutrient availability and uptake [[35]]. The gradual and sustained release of nutrients from organic amendments, like FYM, coupled with the beneficial effects of PGPR in enhancing nutrient availability and plant health, might have contributed to the superior plant heights observed in later harvesting stages [[37]]. This integrated approach reflects the synergy between reduced chemical inputs and natural soil-enhancing practices, offering a sustainable pathway to maintain crop growth.

The number of leaves on berseem plants, a direct indicator of the crop's potential for herbage yield, was also significantly influenced by the variety and nutrient management practices. The higher number of functional leaves in the Mescavi variety during the initial growth stages suggests a genetic inclination towards rapid leaf development, which is beneficial for early forage production. However, the BL-42 variety's capacity to produce a higher number of leaves in the later stages points towards its ability to sustain leaf production over an extended period. This could be due to genetic factors that regulate leaf senescence and photosynthetic efficiency, enabling the plant to continue producing leaves even as it matures. The BL-42 variety, therefore, appears to have a genetic makeup that supports prolonged vegetative growth and productivity, which is crucial for extended forage availability.

In the context of berseem (Trifolium alexandrinum L.) cultivation, the observed variations in green and dry fodder yields can be attributed to a complex interplay of genetic, edaphic, and management factors. The differential performance of the BL-42 variety in terms of higher yield efficiency underscores the genetic predisposition of certain cultivars towards enhanced photosynthetic capacity, nutrient uptake, and growth characteristics [[20]]. This varietal superiority can be linked to genetic traits, such as improved leaf size, root architecture, and nodulation capacity, which are crucial for optimizing biomass production [[39]].

From a nutrient management perspective, the integration of a 75% recommended dose of fertilizers (RDFs) with farmyard manure (FYM) and plant growth-promoting rhizobacteria (PGPR) has demonstrated a synergistic effect on yield [[40]]. This synergy likely arises from the complementary roles of inorganic and organic fertilizers in improving soil fertility [[41]]. Inorganic fertilizers provide immediate nutrient availability, while organic matter from FYM enhances soil structure, water-holding capacity, and microbial activity [[42]]. The inclusion of PGPR further augments nutrient availability through mechanisms like phosphate solubilization, nitrogen fixation, and the production of plant growth hormones [[43]]. The role of nitrogen, particularly in a leguminous crop like berseem, is nuanced. While legumes are known for their nitrogen-fixing abilities through symbiotic relationships with rhizobia, the application of nitrogen fertilizers can still enhance growth and yield [[44]]. This might be due to the energy-intensive nature of biological nitrogen fixation and the potential limitations of endogenous nitrogen fixation under certain soil or climatic conditions. Moreover, the presence of nitrogen fertilizers can stimulate early plant growth before nodulation becomes fully established.

Phosphorus, as a key macronutrient, plays a critical role in energy transfer, photosynthesis, and nutrient transport within the plant [[45]]. Its availability is crucial for root development and early plant growth, which in turn influences biomass accumulation and fodder yield [[46]]. The high performance of specific varieties like BL-42 in the Indo-Gangetic plains indicates a strong genotype–environment interaction. This suggests that varietal selection should be based on adaptability to local agro-climatic conditions, including soil type, temperature, and water availability, to optimize yield [[27]]. Furthermore, the use of municipal solid waste compost represents an integration of agronomic and environmental considerations [[47]]. This approach not only provides a sustainable source of organic matter and nutrients for crops but also contributes to waste recycling and improved soil health over time [[48]].

The study revealed that factors such as the cost of cultivation, gross return, net return, and benefit–cost ratio were not significantly impacted by the study years, as indicated in Table 7. The cost of cultivation remained consistent across the different varieties of berseem, primarily because the seed costs were similar for all the varieties. However, the cultivation cost was lower for treatments using a 75% recommended dose of fertilizers (RDFs) with plant growth-promoting rhizobacteria (PGPR) and 100% RDF, in comparison to the 75% RDF combined with farmyard manure (FYM) and 75% RDF with municipal solid waste compost (MSWC). This is attributed to the higher input costs associated with FYM and MSWC compared to chemical fertilizers.

In terms of economic returns, the BL-42 variety of berseem stood out, exhibiting the highest gross return, net return, and benefit–cost ratio (194,989, 145,142 ₹ ha−1, and 2.91, respectively) compared to the other berseem varieties. Following BL-42, the BL-10 variety also showed significantly greater values in these economic parameters relative to the remaining varieties. This superior economic performance of BL-42 and BL-10 could be due to their higher green fodder yields, which are likely a result of their genetic potential and specific genetic makeup. Supporting this observation, studies [[49], [51]] have also reported that variations in green fodder yields among different berseem varieties, as well as other crops influenced by genotypic differences, can significantly affect the gross return, net return, and benefit–cost ratio. This underscores the importance of variety selection in maximizing the economic viability of berseem cultivation.

Additionally, among the different nutrient management techniques, the application of 75% RDF + FYM + PGPR recorded the highest GR and NR (191,638 and 137,346, ₹ ha−1, respectively) compared to 100% RDF (167,593 and 120,716 ₹ ha−1, respectively). While the benefit–cost ratio was reported as the highest with the use of sole chemical fertilizers (100% RDF), it remained on par with 75% RDF + FYM + PGPR. The maximum B:C ratio of berseem might be due to the lower cost of cultivation as compared to 75% RDF + FYM + PGPR. Greater values for the GR and NR were found in 75% RDF + FYM + PGPR due to its higher green fodder yield. A similar finding indicating that the maximum benefit obtained from 50% RDF + 50% RDN through FYM + Azotobacter in maize was also reported [[52]]. Our results also matched with a similar outcome in berseem as reported by [[15]].

The results indicate that the production efficiency, RPRI, and economic efficiency of berseem varieties were not significantly influenced by the study years of the experiment. However, due to the effect of the different varieties of berseem and integrated nutrient management option production efficiencies, the RPRI and economic efficiency were significantly influenced by the RPRI. The economic efficiency was recorded in the HB-2 variety, which was reported on par with the Mescavi variety. A significantly lower production efficiency, RPRI, and economic efficiency were observed with the HB-1 variety of berseem compared to the rest of the varieties. The highest value of production efficiency, RPRI, and economic efficiency might be due to the higher production of green fodder yield, which depends on the genetic makeup of the varieties of berseem. Similar results were reported earlier by other studies [[50], [53]]. Furthermore, results related to sole chemical fertilizers and a combination of different nutrient management techniques indicated significantly higher production efficiencies, RPRIs, as well as economic efficiencies of berseem, which is due to an increase in the yield [[54]].

Based on the experimental findings, it is evident that the productivity of berseem is significantly influenced by the interplay between different varieties and nutrient management practices. After a thorough two-year study, a key conclusion can be drawn: to achieve higher yields of both green and dry fodder in berseem, the BL-42 variety, when treated with the nutrient management practice of 75% recommended dose of fertilizers (RDFs) combined with farmyard manure (FYM) and plant growth-promoting rhizobacteria (PGPR), is highly recommendable. This recommendation is rooted in the consistent performance of the BL-42 variety under the 75% RDF + FYM + PGPR treatment, which demonstrated a markedly higher production per unit area. This superiority was maintained from the initial first cut through to the last fifth cut, surpassing other combinations of berseem varieties and nutrient management practices. The experimental results, therefore, advocate for the adoption of this specific variety and nutrient management strategy to optimize berseem cultivation, ensuring sustained high yields across multiple harvests.

Further work in the future can be conducted to identify site-specific precise nutrient management approaches for berseem production as well as better nutrient management technologies for higher seed production.

Graph: Figure 1 Weakly average temperature, weekly average relative humidity, and weekly cumulative rainfall during the crop season of 2019–2020 and 2020–2021 (Note: the x-axis indicates the standard meteorological week and month and weekly average temperature (°C) and the weekly average relative humidity (%) is plotted on the left y-axis while the weekly cumulative rainfall (mm) (cyan-colored bars are plotted on the right y-axis).

Table 1 Physicochemical properties of the initial soil sample.

Table 2 Details of the experimental treatments.

Table 3 Effect of varieties and integrated nutrient management on the plant heights of berseem.

Table 4 Effect of varieties and integrated nutrient management on the number of leaves of berseem.

Table 5 Effect of varieties and integrated nutrient management on the leaf area index (LAI) of berseem.

Table 6 Effect of varieties and integrated nutrient management on the number of nodules of berseem varieties.

Table 7 Effect of varieties and integrated nutrient management on the green fodder yield of berseem.

Table 8 Effect of varieties and integrated nutrient management on the economics of berseem.

Table 9 Effect of varieties and integrated nutrient management on the production efficiency, economic efficiency, and RPRI of berseem.

Conceptualization, R.K., R.K.M., H.R. and A.K.; methodology, R.K., P.S.H., S.K., B.B. (Bisworanjita Biswal) and S.B.; software, S.B., P.S.P., G.A. and S.K.; validation B. and R.K.; formal analysis, S.K., R.K., A.K., H.R., S.B. and B.; investigation, S.K., K.B. and R.K.; data curation, S.K., R.K. and G.A.; writing—original draft preparation, P.S.H., P.S.P., S.K. and S.J.; visualization, K.G., P.S.P. and P.S.H. All authors have read and agreed to the published version of the manuscript.

The original contributions presented in the study are included in the article, further inquiries can be directed to the corresponding author.

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

The authors would like to acknowledge the ICAR National Dairy Research Institute, Karnal (India), and ICAR-Central Soil Salinity Research Institute, Karnal (India), for providing the necessary facilities and fellowship to carry out this work.