Assessment of intercropping indices in finger millet and green gram systems under varied nutrient regimes

Introduction

Intercropping cereals with legumes is a sustainable agricultural strategy that enhances cropping system performance by maximizing the efficient use of vital resources such as sunlight, soil water, temperature, and soil nutrients (Foley et al., 2011) [2] . This system not only improves resource-use efficiency but also functions as an eco-functional practice that contributes to diversified diets, lowers the risk of crop losses under biotic and abiotic stress conditions, improves yield stability, and delivers greater economic returns compared with monocropping systems (Tsubo et al., 2005; Bitew et al., 2019) [1,8] . Due to their inherent drought tolerance, finger millet (FM) and green gram (GG) are considered a suitable crop combination for intercropping in drought-affected environments. Finger millet (Eleusine coracana L.), popularly known as ragi, is an important small millet that is widely cultivated under rainfed and dryland conditions across India. Green gram (Vigna radiata L. Wilczek), popularly known as moong, is a protein-rich legume with high digestibility and serves as an important component of human and animal diets. With the rising demand for nutritious food and the increasing emphasis on sustainable agriculture, maintaining soil fertility has become a major concern. Nevertheless, the continuous and imbalanced use of chemical inputs has accelerated nutrient exhaustion, degraded soil quality, and adversely affected crop productivity, threatening the sustainability of modern farming systems. Chemical fertilizers alone cannot sustain long-term soil productivity (Perli et al., 2022) [5] . Integrating organic inputs such as farmyard manure (FYM), vermicompost, biofertilizers, and liquid formulations like Panchagavya, Jivamrut, and Sanjivak with inorganic fertilizers improves nutrient availability, soil fertility, and crop productivity. Therefore, integrated nutrient management is essential for sustainable agriculture. Keeping this in view, the present study was conducted during the kharif season to evaluate the performance of finger millet-green gram intercropping under different nutrient management levels.

Material and Methods experimental site

The field experiment was carried out during Kharif, 2024 at the Zonal Agricultural Research Station, Shendapark, Kolhapur. The average annual rainfall is 1151.6 mm, with 67 rainy days. The annual mean maximum temperature ranges between 25.4 ºC to 33.7ºC while, the annual mean minimum temperature varies from 12.5 ºC to 21.9 ºC.

Soil characters

The soil of the experimental plot was sandy clay loam, low in available Nitrogen (196 kg ha -1 ), medium in available phosphorus (35.3 kg ha -1 ) and low in available potassium (194 kg ha -1 ). The status of organic carbon content (0.67%) was high. The electrical conductivity and pH values were 0.11 dSm -1 and 6.74 respectively.

Experimental details

The experiment was laid out in a Factorial Randomized Block Design (FRBD) comprising eighteen treatment combinations, each replicated three times in which first factor is intercropping C 1: Sole Finger millet, C 2: Finger millet + Green gram (4:2) and C 3: Sole Green gram, while N 1, N 2 , N 3, N 4, N 5, N 6 nutrient levels as a secomd factor. For the sowing of seed, very small furrow lines were opened with the help of marker at a distance of 30 cm between the row and sowing of the crop was done on 13 th July, 2024. The recommended seed rate of 15 kg ha -1 for green gram and 5 kg ha -1 for finger millet was used. Each gross plot measured 4.8 m × 6.0 m, and the net plot area was maintained at 3.6 m × 4.8 m.

Intercropping indices

Statistically analysis of intercropping indices such as LER, CEY, RCC, ATER and MAI are evaluated by using 3 x 6 factorial randomized block design in intercropping system Land Equivalent Ratio (LER) LER is defined as the relative land area under sole crop that is required to produce yields achieved in intercropping. The LER was worked out by using the following formula given by Willey (1979).

Where, Y a and Y b: Individual crop yields under intercropping S a and S b: Individual crop yields under sole cropping.

Crop Equivalent Yield (CEY)

Crop Equivalent Yield (CEY) is a standardized measure used in agriculture to compare the yields of different crops by converting them into the yield of a single reference crop, usually the main or most valuable crop in a cropping system. To assess the economic productivity of the intercropping systems, Crop Equivalent Yield (CEY) was calculated using the following formula:

Where, Yields are expressed in tons per hectare (t ha -1 ) or (q ha -1 ) Market prices (in ₹ ton -1 ) were obtained from the local agricultural market at the time of harvest

Relative crowding coefficient (RCC) (K)

Each crop in the intercropping has its RCC (K) which provides a measure of whether that component has produced more or fewer yields than expected. If the K value is >1, then there is a yield advantage of crop A in intercropping but if the K value is equal to or less than 1, it means there is no yield advantages or disadvantage respectively.

Monetary Advantage index (MAI)

In intercropping, the Monetary Advantage Index (MAI) is a metric used to evaluate the economic benefit of growing two or more crops together compared to growing them separately (i.e., in monoculture). It helps determine whether intercropping is more profitable than sole cropping The economic advantage of the cropping system can determine by the monetary advantage index [4] .

Result and Discussion

Finger Millet Equivalent Yield

The data on finger millet equivalent yield (FMEY) as influenced by intercropping of finger millet with green gram are presented in Table 3. Among the treatment combinations, finger millet + green gram (4:2) with the application of 100% RDF (C₂N₁) recorded the highest FMEY (36.61 q ha⁻¹). This was followed by finger millet + green gram (4:2) receiving 75% RDF along with soil application of Azospirillum (2 kg ha⁻¹) and PSB (2 kg ha⁻¹) in combination with foliar spray of 2% 19:19:19 at 15 and 30 DAS (C₂N₃).The superior finger millet equivalent yield recorded under the 100% RDF treatment may be attributed to the adequate supply of essential nutrients, which promoted better crop growth, enhanced photosynthetic activity, and increased biomass production. The slightly lower FMEY observed under the 75% RDF treatment supplemented with biofertilizers and foliar nutrition indicates that although biofertilizers improve nutrient availability and uptake, they may not completely offset the reduction in the recommended fertilizer dose. Similar findings were reported by Padhi et al. (2010) [4] , Jena et al. (2000) [3] , and Ramamoorthy et al. (2003) [7] , who also emphasized the importance of balanced nutrient management for maximizing productivity in intercropping systems.

millet + green gram (4:2) with the application of 100% Recommended Dose of Fertilizers (RDF) (C₂N₁) recorded the highest GGEY of 18.09 q ha⁻¹. The second highest GGEY was obtained with finger millet + green gram (4:2) receiving 75% RDF along with soil application of Azospirillum (2 kg ha⁻¹) and PSB (2 kg ha⁻¹) in combination with foliar spray of 2% 19:19:19 at 15 and 30 DAS (C₂N₃). The superior GGEY recorded under the 100% RDF treatment could be attributed to the adequate and balanced availability of essential nutrients, which supported optimum crop growth and higher productivity of green gram in the intercropping system. Adequate nutrient supply enhanced physiological activities, improved nodulation, and promoted better grain filling in the legume crop. Although the integrated nutrient management treatment (C₂N₃) also produced higher GGEY, it remained slightly lower than the 100% RDF treatment, probably because the reduced fertilizer dose could not completely meet the crop's nutrient requirement. Similar findings were reported by Padhi et al. (2010) [4] , Jena et al. (2000) [3] , and Ramamoorthy et al. (2003) [7] , who emphasized the significance of balanced nutrient management for achieving higher legume productivity under intercropping systems.

Relative Crowding Coefficient (RCC)

The effect of finger millet-green gram intercropping on the Relative Crowding Coefficient (RCC) is presented in Table 3. Among the treatment combinations evaluated, finger millet + green gram (4:2) supplied with 50% RDF along with 50% RDN through FYM (C₂N₆) exhibited the highest RCC value of 8.34. The lowest RCC value (1.75) was recorded under the treatment receiving 75% RDF combined with soil application of Azospirillum (2 kg ha⁻¹) and PSB (2 kg ha⁻¹) (C₂N₂). The higher RCC obtained under C₂N₆ reflects a more favourable competitive relationship and better complementary use of resources between finger millet and green gram. This could be attributed to the combined use of organic manure and inorganic fertilizers, which improved nutrient availability throughout the crop growth period and promoted efficient utilization of growth resources by both component crops. In comparison, the lower RCC observed in C₂N₂ may be associated with the reduced inorganic fertilizer level, which, despite the addition of biofertilizers, was insufficient to achieve optimum nutrient availability and competitive performance of the intercrops. These results are in agreement with the findings of Pradhan et al. (2024) [6] , who also reported that integrated nutrient management enhances crop compatibility, resource-use efficiency, and productivity in intercropping systems.

Area Time Equivalent Ratio

The results pertaining to the Area Time Equivalent Ratio (ATER) of finger millet-green gram intercropping are presented in Table 3 The superior ATER recorded under C₂N₆ and C₂N₄ reflects more efficient utilization of land as well as crop duration in the intercropping system. This improvement may be attributed to the combined effect of balanced nutrient supply, enhanced soil fertility through FYM and Panchagavya, and increased microbial activity resulting from biofertilizer application, which together promoted better crop growth and improved overall system productivity. In contrast, the lower ATER recorded under C₂N₂ indicates comparatively less efficient use of available land and time resources, which may be due to reduced nutrient availability and the absence of integrated nutrient sources.

Monetary Advantage Index (MAI)

The effect of finger millet-green gram intercropping on the Monetary Advantage Index (MAI) is presented in Table 3. Among the different treatment combinations, finger millet + green gram (4:2) receiving 50% RDF along with 50% RDN through FYM (C₂N₆) registered the highest MAI of ₹38,279 ha⁻¹. However, the lowest MAI was recorded under the treatment comprising finger millet + green gram (4:2) supplied with 75% RDF in combination with soil application of Azospirillum (2 kg ha⁻¹) and PSB (2 kg ha⁻¹) (C₂N₂). The higher MAI obtained under C₂N₆ reflects the greater economic advantage of this intercropping system. This may be attributed to the integrated use of organic and inorganic nutrient sources, which improved nutrient use efficiency, stimulated microbial activity, and ensured a steady supply of nutrients during the crop growth period. Consequently, these factors enhanced crop productivity and increased economic returns. In comparison, the lower MAI recorded under C₂N₂ may be associated with comparatively lower nutrient availability, resulting in reduced crop productivity and consequently lower economic benefits from the intercropping system. Thus, integrated nutrient management using both organic and inorganic sources play a key role in maximizing the monetary advantage in intercropping systems.

Conclusions

The experimental results revealed that the highest Land Equivalent Ratio (LER) of 1.41 was obtained under the treatment combination of finger millet + green gram (4:2) with the application of 50% RDF + 50% RDN through FYM (C₂N₆). The maximum Finger Millet Equivalent Yield (FMEY) of 36.61 q ha⁻¹ and Green Gram Equivalent Yield (GGEY) of 18.09 q ha⁻¹ were recorded under finger millet + green gram (4:2) receiving 100% RDF (C₂N₁). Likewise, the highest values of Relative Crowding Coefficient (RCC) (8.34), Area Time Equivalent Ratio (ATER) (1.16), and Monetary Advantage Index (MAI) (₹38,279 ha⁻¹) were also observed in the treatment comprising finger millet + green gram (4:2) with 50% RDF + 50% RDN through FYM (C₂N₆).

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