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Modelling of soil nutrient budgets: an assessment of agricultural sustainability in Nepal
| Publication Type | Journal Article |
| Year of Publication | 1999 |
| Authors | Brown, S,; Schreier, H,; Shah, P, B.; Lavkulich, L, M. |
| Journal Title | Soil Use and Management |
| Volume | 15 |
| Pagination | 101-108 |
| ISBN Number | 0266-0032 |
| Key Words | soil fertility; nutrient balance; models; sustainability; agriculture; land management; irrigation; wheat; rice; dry farming; maize; nitrogen fixation; fertilizers; erosion; Triticum; Oryza; Zea mays |
| Abstract | Sustaining soil fertility under agricultural intensification and expansion onto marginal lands is a significant challenge in the Nepalese Middle Mountains. In a detailed watershed study it was shown that the overall soil fertility is poor, forest soils display the poorest conditions as a result of biomass removal, and sustaining agriculture is questionable due to the transformation from traditional to multiple cropping systems. Parent material was a significant factor influencing low phosphorus status while insufficient inputs created deficiencies in total carbon, nitrogen and bases. A nutrient budget model was developed to assess inputs, redistribution and losses relative to soil fertility. Yield, input and management data obtained from farm interviews, and soil analysis data were used in the calculation of nutrient budgets. Results from modelling showed declining soil fertility under rainfed agriculture, forest and rangelands, and marginal conditions under irrigated agriculture subject tointensive cultivation. Nutrient deficits were low for irrigated rice-wheat systems, which benefit from nutrient inputs via sediments and irrigation waters, but the introduction of triple cropping showed greater deficits. Nutrient balances were most critical under rainfed maize production where 94% of the farms were in deficit. Current shortages of organic matter made elimination of nutrient deficits problematic but improvement of composting, biological N-fixation and fertilizer efficiency and reducing erosion were potential options. |
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