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- Chala, Workneh Bedada, et al.
(author)
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Soil nutrient build-up, input interaction effects and plot level N and P balances under long-term addition of compost and NP fertilizer
- 2016
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In: Agriculture, Ecosystems and Environment. - : Elsevier BV. - 0167-8809 .- 1873-2305. ; 218, s. 220-231
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Journal article (peer-reviewed)abstract
- Decline in farmland soil fertility due to nutrient depletion is a concern for smallholder farmers in the highlands of Ethiopia. In this study we tested if long-term addition of compost, either alone or in combination with nitrogen (N) and phosphorous (P) fertilizer, affected available soil nutrient status, grain/tuber harvests, agronomic N use efficiency, and plot level N and P nutrient balances. The on-farm experiments were conducted on four farm fields for up to 6 years in Beseku, Ethiopia. A randomized complete block design was used, with four treatments: full dose of compost applied alone at 2.4 t ha(-1) DW organic matter (C); full dose of fertilizer (F); half compost and half fertilizer (CF); and, unfertilized control. In the upper 10 cm of the surface soil, several Mehlich-3 extractable nutrients (B, Ca, K, Mg, P, S, and Zn) had significantly higher concentrations in the C treatment (P < 0.01), and some in the CF treatment (P < 0.05) than in the control. Phosphorus was the only nutrient with a higher concentration in the F treatment than the control. Maize and faba bean showed added benefits (synergy) in terms of yield increase in the CF treatment and a better agronomic efficiency for added N. Plot level N balances were negative for all treatments except C, with strong depletion in the control (-76 kg N ha(-1) yr(-1)) and F (-65 kg N ha(-1) yr(-1)) treatments. When the N balance was compared to measured change in soil N, the F and control treatments were significantly (P < 0.05) lower than zero. N in the CF and C treatments was close to steady-state, i.e., the input of N in organic matter compensated for the loss of N through mineralization. The control treatment had a negative P balance of 11 kg P ha(-1) yr(-1), with moderately negative balance of 4 kg P ha(-1) yr(-1) in the C treatment. The CF and F treatments had positive P balances. Thus, the addition of compost, both alone or in combination with mineral fertilizer, can prevent N and reduce P mining and improve the nutrient status of the soil. When only NP fertilizer was used, the crop utilized all N that was mineralized indicating that the crop was N limited. (C) 2015 Elsevier B.V. All rights reserved.
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