Yield Gap Analysis of Blackgram Through Cluster Frontline Demonstrations in Salem District of Tamil Nadu

Blackgram (Vigna mungo L.), commonly known as urdbean, is a short-duration pulse  crop known for its high protein content of 25-26%. India is the largest producer and consumer of blackgram, cultivating it as a solo crop, intercropand catch crop. India’s blackgram production reached 2.78 million tonnes from an acreage of 4.63 million hectares at an average productivity  of 614 kg/ha. Blackgram accounts for 11% of India’s total pulses production (Anonymous, 2022). 
 
In Tamil Nadu, blackgram contributes significantly to the state’s agriculture, with an annual production of about 28.4 lakh tonnes from 47.6 lakh hectares of area, at an average productivity of 596 kg/ha in 2021-22 (Anonymous, 2022).  In Salem district, blackgram occupies a major area next to cowpea and greengram. However, the productivity of blackgram in Salem district is 456 kg/ha, which is considerably lower than the national and state averages, indicating a substantial yield gap. Scarcity of quality seeds of high-yielding and disease-tolerant varietiesis resulting in increased incidences of pests and diseases particularly yellow mosaic virus disease. Use of local and photosensitive varieties, erratic rainfall patterns, cultivation on poor and marginal lands, seed broadcastingand the absence of seed treatment with bio-fertilizers contribute to suboptimal yields. Inadequate application of micronutrients and poor pest and disease management practices are prevalent among growers. The partial adoption of recommended agricultural practices widens the technology gap, hindering efforts to increase blackgram production in the district.
 
To address these challenges, the Krishi Vigyan Kendra (KVK) initiated a project aimed at enhancing production and productivity through cluster frontline demonstrations (CFLDs) using the latest technologies. This initiative sought to systematically bridge the technology gap and empower farmers with the knowledge and resources necessary to improve blackgram cultivation practices and yield outcomes. Through this comprehensive approach, the project aimed to provide farmers with access to quality seeds, introduce improved cultivation techniquesand promote the use of bio-fertilizers and micronutrients. Through better understanding of pest and disease management, adapting suitable technologies to the local agro-climatic conditions, the project intended to narrow down the yield gap and enhance the overall productivity of blackgram in Salem district.

The Krishi Vigyan Kendra (KVK), Salem, conducted the present investigation on cluster frontline demonstrations during the summer seasons from 2017 to 2021. One hundred frontline demonstrations on blackgram (variety VBN 8)   were laid out in an area of 50 hectares across five villages viz., Mallikundam, Thumbathulipatti, Kongupatti, Anniyampatti and Manjini in Salem district in Tamil Nadu. The objective of these cluster frontline demonstrations was to increase blackgram production. The demonstrations used blackgram (variety VBN 8) seeds and mechanized sowing techniques. Specifically, a seed drill was calibrated for blackgram using the metering mechanism provided in the drill. The zero-till ferti seed-drill utilized a distinct type of furrow opener, which created slits in the untilled soil with minimal disturbance. The recommended seed rate of 8 kg per hectare was sown in 30 cm row spacing. Before sowing, the seeds were soaked for three hours to ensure uniform moisture content and the soil moisture content at the time of sowing was 25%.
 
KVK demonstrated various materials and technologies for conducting frontline demonstrations (FLDs) with the farmers (Table 1). The input materials were provided to the farmers, who were trained to follow the package and practices for blackgram cultivation as recommended by the Tamil Nadu Agricultural University, Coimbatore. This included seed treatment, bio-fertilizer inoculation, fertilizer application, water and weed managementand insect pest management. In the local check plots, farmers followed traditional practices using existing varieties. Using the computations described by Marlabeedu et al., (2022) for analyzing the technology gap, technology index, extension gap and economic parameters in comparison with farmers practices, the percent yield comparison of improved practices with local check, district and state average was computed. The yield impact was also evaluated:


       
Data were collected from participating farmers using a well-structured questionnaire after the harvesting and marketing of the blackgram. Yield data were obtained from individual farmersand the weighted mean yield was calculated. The percentage yield increase over farmers’ practices was determined by comparing the average yield of the CFLD (Cluster Front Line Demonstration) plots with that of the farmers’ practices. The cost of cultivation was calculated for both CFLD and farmers’ practices, including the costs of inputs such as seeds, fertilizers (both chemical and bio-fertilizers), pesticides, herbicides, hired labor (excluding family labor), field preparation, sowing, harvestingand transportation. Average gross and net returns were calculated based on the sale price of the grain in the local market. The benefit:cost ratio was determined by dividing the gross return by the corresponding cost of cultivation (Kumari et al., 2007).
 

Growth and yield characters of blackgram
 
The demonstrations showed a 21.9% higher yield as compared to the local practices, which recorded 6.8 q/ha. On average, the yield from the demonstrations was higher than that of the check variety. The average yield during the 2017 season was 8.15 q/ha and during the 2018 season, it was 8.36 q/ha. The benefit cost ratio of the demonstrations was 3.46 in 2017 and 3.32 in 2018 (Table 2). These results are in agreement with the findings of Rupesh et al., (2017), who reported benefit: cost ratios of 2.18 and 2.22 for conventional varieties in 2017 and 2018, respectively. The data indicated a positive impact of cluster frontline demonstrations on increasing blackgram yields in the Salem district in Tamil Nadu. The benefit:cost ratio was consistently higher under the demonstration conditions as compared to control in all the study years, with an average   increase of 18.24% over the control. Throughout the study period, there was a strong emphasis on educating farmers through various techniques to adopt improved agricultural practices, aiming to reduce the extension gap (Tiwari and Saxena, 2001). Different physiological parameters were observed in samples collected from various farmers’ fields. The demonstration samples exhibited a higher germination percentage as compared to the check plots. The average field emergence percentage for the demonstration samples was 79.69%, representing a 12% increase over the check variety’s 67.17% (Table 3).




 
An increase in plant height was observed in the demo samples as compared to the check plots. The average plant height of the demo samples was 44.79 cm, while the check plots had an average height of 35.72 cm (Table 3). Similar increases in plant height have been reported in lettuce using Pseudomonas bio-fertilizer (Rostaminia et al., 2020; Santana Fernandez et al., 2021). Furthermore, spraying with Pulse Wonder increased plant height in blackgram (Kamaleshwaran and Karthiga, 2021). The number of pods per plant was also higher in the demo samples (50.93) than in the check plots (41.07) (Table 3)    directly influencing seed yield. Similar results were reported in blackgram by foliar application of Pulse Wonder at 5 kg/ha during flowering and 15 days after the first DAS spray. This treatment resulted in significantly higher plant height, number of pods per plant, seeds per pod, seed yield (q/ha), straw yield (q/ha), harvest index (%), net return (Rs) and benefit: Cost ratio as compared to other foliar spray treatments (Devaraju and Senthivel, 2018).
 
Molla et al. (2012) demonstrated increased plant height, number of fruits per plant, individual fruit sizeand enhanced yield in tomatoes through the application of   Trichoderma viride bio-fertilizer. Similar results were reported in wheat by Mahato et al., (2018). Marimuthu and Surendran (2015) reported that application of 100% recommended dose of NPK + DAP 2% + TNAU Pulse Wonder 5.0 kg/ha recorded significantly higher plant growth, number of pods per plant, yield of blackgramand benefit:cost ratio over  control. Sujatha and Ambika (2016) reported that designer seeds fortified with 1% KCl for 6 hours followed by polymer coating at 3 ml/kg, carbendazim at 2 g/kg, imidacloprid at 2 ml/kg, Trichoderma viride at 4 g/kg, enhanced plant growth and yield. This treatment increased   number of pods per plant, pod yield per plot (g)and seed yield per plant (g), with fewer days to 50% flowering and reduced pest and disease incidence. Similar results were also observed in paddy (Sujatha and Ambika, 2018) and cotton (Sujatha and Ambika, 2020).
 
The increases in plant growth and yield might be due to   higher supply of nutrients at flower initiation and pod formation stages, leading to efficient translocation of photosynthates from source to sink through foliar application of nutrient spray like Pulse Wonder (Kamaleshwaran and Karthiga, 2021; Devaraju and Senthivel, 2018). Additionally, the designer seeds provide protection during initial stages of establishment from seed-borne pathogens and improve nutrient use efficiency via bio-fertilizer. Trichoderma and Pseudomonas bio-fertilizers assist in the solubilization and sequestration of essential plant nutrients such as P, Mn, Fe and Zn, thereby enhance plant growth (Lal et al., 2013). The increased root biomass, accumulation of nitrogen and production of plant growth hormones such as gibberellins and cytokinins by these inoculants promote seedling growth. These results positively influenced the benefit: Cost ratio.
 
To estimate the yield gap, the potential yield of the crop was compared with the yield from the demonstration plots. The yield gap analysis was assessed using the technology index, extension gap and technology gap. The extension gap, which illustrates the variation in yield between the farmer’s plots and the demonstration plots, ranged from 1.25 to 1.89 q/ha over the investigation period, with an average of 1.49 q/ha over three years (Table 4). This gap highlights the need to educate and train farmers in adopting yield-maximizing technologies to close this significant practice gap. Extension yield gaps indicate a lack of awareness and adoption of improved farm technologies among farmers (Vedna et al., 2007). The new technologies will eventually convince farmers to discontinue the old technology and to adopt new technology. This finding is in corroboration with the findings of Hiremath and Nagaraju (2010) and Upesh Kumar et al., (2023) in blackgram.


 
Technology gap
 
The technology gap representing the difference between the potential yield of the crop and the demonstration yield, ranged from 0.05 to 0.56 q/ha, with an average of 0.39 q/ha (Table 4). Farmers are negatively impacted by the technology gap due to insufficient extension efforts and a lack of  demonstrations of improved technologies. This gap can be attributed to various factors, including crop suitability, soil fertility status, fluctuations in sowing dates and meteorological conditions. This can also be   attributed to   lack of irrigation, uneven rainfall, variations in soil fertility, cultivation on marginal lands, unfavorable weather conditions and specific crop management challenges. These issues hinder the ability to fully harness the yield potential of crop cultivars (Choudhary et al., 2009). These observations highlight the urgent need for location-specific crop management practices to bridge the gap between potential and actual yields in demonstration plots (Vedna et al., 2007), along with strengthening of irrigation infrastructure in the region (Choudhary, 2009).   Similar findings were also reported by Singh et al., (2021) in summer mungbean.
 
Technology index
 
Technology index indicates the feasibility of generated farm technologies in the farmers’ fields under prevailing agro climatic situations (Vedna et al., 2007). A lower technology index value suggests greater feasibility. This index is a percentage (%) based on the technology gap, where a higher value indicates lower adoption of improved technologies by farmers. The three-year technology index in demonstrations averaged 26.41%, ranging from 0.57% to 6.43% (Table 4). The low technology index is attributed to the interventions by KVK scientists and the adoption of yield-maximizing practices for blackgram by the farmers. Timely and need-based recommendations from KVK scientists and extension staff along with favorable climate conditions and a low fpests and diseases incidence supported the lower technology index.
 
Economics
 
Yield, variable costsand the difference between market price and minimum support price are the primary determinants of economic returns. Input costs and labor wages fluctuated over time. The economic viability of enhanced methods over traditional farmers’ practices was determined based on the input and output costs at the time of the study as compared to traditional practices. Where the average cost of cultivation, gross returns and net returns were Rs. 28,160/ha, Rs. 56,531/ha and Rs. 28,371/ha, respectively, with an average benefit:cost ratio of 2.01. Improved practices recorded a higher average cost of cultivation (Rs. 30,490/ha), gross returns (Rs. 68,913/ha) and net returns (Rs. 38,423/ha) (Table 5). Similar economic benefits owing to adoption of improved technology interventions were also reported by Meena et al., (2021) and Reager et al., (2020). Additionally, on an average of five years, the improved practices generated an additional gross return of Rs. 12,382/ha as compared to traditional practices, with a benefit:cost ratio of 2.26 (Table 5). Higher benefit:cost ratio in demonstrations could be the result of higher yield due to adoption of improved practices which were missing in local check plots. Singh et al., (2017) observed similar results in mungbean and Kantwa et al., 2024 in chickpea, however, Kumar and Boparai (2020) observed a B:C ratio in the range of 1.92 to 2.44 during their study period.

Cluster frontline demonstrations on blackgram, were conducted in five villages  and the results highlighted a significant difference in yield across two consecutive years. In 2021, the average yield was 11.47 q/ha, while in 2017  season, it was 8.50 q/ha. The benefit:cost ratio for these years was 4.04 and 2.27, respectively, for the demonstration plots. An impressive 81.50% increase in yield was observed in the demonstration plots as compared to the farmers’ conventional practices. These results underscore the potential for achieving higher yields through   dissemination of scientific knowledge to farmers,   provision of quality seeds, need-based inputs and the proper application of these inputs. The combination of  inputs  such as designer seeds, application of TNAU Pulse Wonderand bio-fertilizers along with scientific guidance, significantly enhanced the crop’s potential yield. Furthermore, the demonstrations showed that adopting these advanced practices by farmers not only improves the yield but also ensures sustainable agricultural practices. This approach leads to better resource management and can be pivotal in uplifting the economic status of the farmers.

The authors declare that there are no conflicts of interest regarding the publication of this article.