Long-term yield trend and sustainability of rainfed soybean–wheat system through farmyard manure application in a sandy loam soil of the Indian Himalayas |
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Authors: | S Kundu Ranjan Bhattacharyya Ved Prakash H S Gupta H Pathak J K Ladha |
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Institution: | (1) Vivekananda Institute of Hill Agriculture (Indian Council of Agricultural Research), Uttaranchal, Almora 263 601, India;(2) International Rice Research Institute-India, CG Block, National Agriculture Science Centre Complex, DPS Marg, Pusa, New Delhi, 110 012, India |
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Abstract: | A long-term (30 years) soybean–wheat experiment was conducted at Hawalbagh, Almora, India to study the effects of organic
and inorganic sources of nutrients on grain yield trends of rainfed soybean (Glycine
max)–wheat (Triticum
aestivum) system and nutrient status (soil C, N, P and K) in a sandy loam soil (Typic Haplaquept). The unfertilized plot supported
0.56 Mg ha−1 of soybean yield and 0.71 Mg ha−1 of wheat yield (average yield of 30 years). Soybean responded to inorganic NPK application and the yield increased significantly
to 0.87 Mg ha−1 with NPK. Maximum yields of soybean (2.84 Mg ha−1) and residual wheat (1.88 Mg ha−1) were obtained in the plots under NPK + farmyard manure (FYM) treatment, which were significantly higher than yields observed
under other treatments. Soybean yields in the plots under the unfertilized and the inorganic fertilizer treatments decreased
with time, whereas yields increased significantly in the plots under N + FYM and NPK + FYM treatments. At the end of 30 years,
total soil organic C (SOC) and total N concentrations increased in all the treatments. Soils under NPK + FYM-treated plots
contained higher SOC and total N by 89 and 58% in the 0–45 cm soil layer, respectively, over that of the initial status. Hence,
the decline in yields might be due to decline in available P and K status of soil. Combined use of NPK and FYM increased SOC,
oxidizable SOC, total N, total P, Olsen P, and ammonium acetate exchangeable K by 37.8, 42.0, 20.8, 30.2, 25.0, and 52.7%,
respectively, at 0–45 cm soil layer compared to application of NPK through inorganic fertilizers. However, the soil profiles
under all the treatments had a net loss of nonexchangeable K, ranging from 172 kg ha−1 under treatment NK to a maximum of 960 kg ha−1 under NPK + FYM after 30 years of cropping. Depletion of available P and K might have contributed to the soybean yield decline
in treatments where manure was not applied. The study also showed that although the combined NPK and FYM application sustained
long-term productivity of the soybean–wheat system, increased K input is required to maintain soil nonexchangeable K level. |
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Keywords: | Long-term experiment Soybean– wheat system Rainfed cropping Farmyard manure Yield sustainability Soil fertility |
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