Although continuous use of inorganic fertilizers in the past decades in India helped to realize increased crop productivity initially, has not been so successful in its sustenance. Hence, organic farming in recent years is gaining impetus due to realization of inherent advantages it confers in sustaining crop production and also in maintaining dynamic soil nutrient status and safe environment. Use of farmyard manure with other organic amendments like vermicompost, neem seed cake, bio-fertilizers and bio-pesticides, etc., has become imperative to go for rational use of organic inputs for the management of soil organic matter for sustainable crop production.
A field experiment to know the effect of application of organics on the productivity of groundnut (cv. JL-24) was conducted in organic deficient Vertisols (Medium black soil) under rainfed farming situations at the Main Agricultural Research Station, University of Agricultural Sciences, Dharwad, Karnataka (India) during rainy season of 2004. The chemical test values of soil were 7.35 pH, 0.13 dS/m EC, 4.30 % CaCO3, 0.45 % organic carbon, 252 kg available N/ha, 11.90 kg available P/ha, 297.60 kg available K/ha, 10.95 ppm Fe (DTPA-extractable iron) and 4.45 ppm Zn (DTPA-extractable zinc). The total rainfall received during the crop growth period of groundnut was 423.8 mm and the crop experienced initial moisture stress for a period of 38 days.
The experiment consisted of T1- organic farming, included the application of farmyard manure (FYM) @ 75 t/ha and Vermicompost @ 2 t/ha. The seeds were treated with biofertilizers such as rhizobium, phosphate solubilzing bacteria (Pseudomonas striata) and plant growth promoting rhizobacteria (PGPR). In order to encounter biotic stresses biopesticides such as neem seed cake @ 500 kg/ha (soil application), seed treatment with Trichoderma harzianum @ 5 g/kg seed and spraying crop with 5 % neem seed kernel extract were used. Another treatment T2- Inorganic farming involves seed treatment with Captan (3 g/kg seed), application of recommended dose of inorganic fertilizers (25 kg N, 75 kg P2O5 and 25 kg K2O/ha) and chemical pesticides. The FYM was applied 29 days before sowing and was thoroughly incorporated into the soil. Neem cake and Vermicompost in T1 and inorganic fertilizers in T2 were applied in the seed rows at the time of sowing. The plot size for each treatment was 50 m x 20 m (100 m2). The seeds of JL 24 (a Spanish bunch groundnut cultivar) were hand dibbled at planting geometry of 30 cm x 10 cm. Groundnut plots were kept weed free by integrated weed management practices. The maturity duration of the groundnut crop was 110 days. At the time of harvest, 60 plants were taken at random in each treatment to record observations on yield components and yield/plant. The crop was uprooted and pods were allowed to sun dry along with haulm for a period one-week. Pods were plucked, dried and cleaned and dry pod yield per plot was recorded.
The results indicated that organic farming in groundnut produced 18.18 and 22.09 % higher dry pod yield and higher kernel yield over inorganic farming (2970 and 2345 kg dry pod and kernel yield/ha, respectively). Further, use of organics in groundnut production also resulted in higher pod number/plant (23.04 %), dry pod weight/plant (13.08 %), double seeded pods (6.62 %), shelling percent (3.34 %), sound mature kernels (3.94%), 100-kernel weight (0.14%) and harvest index (3.16 %) as compared to inorganic farming (20.4, 28.912 g, 136, 78.94 %, 88.42 % 50.76 g and 0.411, respectively). Groundnut crop in organically amended plot did not show moisture stress during the period of dry spell of 38 days due to greater moisture conservation. On the contrary, groundnut in inorganic farming showed moderate to severe moisture stress during same initial dry spell period.
The economic analysis of groundnut production reveals that organic and inorganic groundnut productions recorded a sum of Rs. 30,270 and Rs.36,003/ha net returns, respectively. Thus, the studies indicate that the groundnut productivity is not only higher in organic farming compared to inorganic farming in very first year of practice, but would improve further and may become sustainable in the subsequent years of organic farming significantly.