Smith Jo, Yeluripati Jagadeesh, Smith Pete, Nayak Dali Rani
School of Biological Science, University of Aberdeen, Aberdeen, UK.
Information and Computational Sciences, James Hutton Institute, Aberdeen, UK.
Nat Sustain. 2020 Mar;3:247-252. doi: 10.1038/s41893-019-0469-x. Epub 2020 Jan 20.
Under current trends, 60% of India's population (>10% of people on Earth) will experience severe food deficiencies by 2050. Increased production is urgently needed, but high costs and volatile prices are driving farmers into debt. Zero budget natural farming (ZBNF) is a grassroots movement that aims to improve farm viability by reducing costs. In Andhra Pradesh alone, 523,000 farmers have converted 13% of productive agricultural area to ZBNF. However, sustainability of ZBNF is questioned because external nutrient inputs are limited, which could cause a crash in food production. Here, we show that ZBNF is likely to reduce soil degradation and could provide yield benefits for low-input farmers. Nitrogen fixation, either by free-living nitrogen fixers in soil or symbiotic nitrogen fixers in legumes, is likely to provide the major portion of nitrogen available to crops. However, even with maximum potential nitrogen fixation and release, only 52-80% of the national average nitrogen applied as fertilizer is expected to be supplied. Therefore, in higher-input systems, yield penalties are likely. Since biological fixation from the atmosphere is possible only with nitrogen, ZBNF could limit the supply of other nutrients. Further research is needed in higher-input systems to ensure that mass conversion to ZBNF does not limit India's capacity to feed itself.
按照当前趋势，到2050年，印度60%的人口（超过地球上10%的人口）将面临严重的食物短缺。迫切需要增加粮食产量，但高成本和价格波动正使农民陷入债务困境。零预算自然农法（ZBNF）是一场基层运动，旨在通过降低成本来提高农场的生存能力。仅在安得拉邦，就有52.3万农民将13%的农业生产用地转变为采用零预算自然农法。然而，零预算自然农法的可持续性受到质疑，因为外部养分投入有限，这可能导致粮食产量暴跌。在此，我们表明，零预算自然农法可能会减少土壤退化，并可能为低投入农户带来产量提升。土壤中自生固氮菌或豆科植物中的共生固氮菌进行的固氮作用，可能会为作物提供大部分可利用的氮。然而，即便固氮和氮释放达到最大潜力，预计所提供的氮也仅为全国平均化肥施用量的52%至80%。因此，在高投入系统中，产量可能会下降。由于只有氮能够通过生物作用从大气中固定下来，零预算自然农法可能会限制其他养分的供应。在高投入系统中还需要进一步研究，以确保大规模转向零预算自然农法不会限制印度的粮食自给能力。
