Productivity in maize based cropping systems under various soil-water-nutrient management strategies in a semi-arid, alfisol environment in East Africa
Productivity in maize based cropping systems under various soil-water-nutrient management strategies in a semi-arid, alfisol environment in East Africa
复制标题
DOI：
10.1016/s0378-3774(02)00151-8
复制
发表时间：
2003-04-02
影响因子：
6.7
通讯作者：
Nordbo, E
中科院分区：
文献类型：
--
作者：
Jensen, JR;Bernhard, RH;Nordbo, E
在坦桑尼亚半干旱地区的两个地点进行了为期3年的田间试验，目的是分析通过结合节水和养分管理提高玉米种植系统生产力的潜力。这两个地点的土壤差异主要在于风化程度、粘化层粘粒含量和土壤总体肥力水平。试验期间的降雨状况包括干旱年、正常降雨年和多雨年，扎垄提高了对降雨和肥料的响应，增加了土壤植物有效氮的供应，增强了间作对粮食总产量和收获指数的积极影响。结合对年降雨量和氮，磷肥条件下绑垄概括为简单的经验函数占98%的产量方差。通过将绑垄耕作与矿物氮和磷肥的投入相结合，可以实现比“农民做法”（即平地耕作和不施肥）大幅度的增产，使玉米籽粒产量达到农民做法下约1兆公顷（-1）的现行产量的6倍。同样，在接近正常降雨量的年份，在高肥料投入下，谷物产量可以增加两倍，达到6公斤/公顷/毫米/公顷的水平。结垄的效应既有正效应，也有负效应，在年降雨量接近正常值时（500-600 mm），结垄的正效应占主导地位，而在年降雨量大于700-900 mm时，结垄的负效应占主导地位，但施肥可以部分缓解结垄的负效应。土壤风化程度越高，对水分亏缺和过剩的敏感性越高，降雨范围越窄，起垄效果越好。结果表明，在降雨量接近正常到偏干的条件下，不投入养分的结垄方式在两个试验点的平均增产率分别为34%和42%，在土壤质量较好、降雨量略高、市场整合度较好的试验点，结垄方式具有潜在的经济效益。因此，一个以生存为导向的家庭将最大限度地提高玉米-豇豆间作系统的盈利能力，通过使用捆绑起垄和没有肥料投入，而一个以市场为导向的更资源丰富的家庭将最大限度地提高利润，从捆绑起垄和高肥料投入的组合。牛粪的稀缺和施用的总成本使牛粪无法成为该地区大多数农民的一种可行和重要的营养投入选择。与豇豆间作是一个重要的经济因素，目前受到疾病和低作物密度的限制。这项研究强调了从耕作制度的角度分析水土保持技术的重要性，并支持在年降雨量为500-700毫米的半干旱环境中重点关注水土保持措施，如系垄。然而，认识到系垄技术的潜在缺点，还建议研究替代做法，在最小土壤扰动的情况下改善原位水分保持。(C)2002 Elsevier Science B. V.保留所有权利。
A 3-year field experiment was undertaken at two sites in semi-arid Tanzania with the objective of analysing the potential for improving the productivity of maize based cropping systems through combinations of water conservation and nutrient management. The soils at the two sites differed mainly in their degree of weathering, clay content of the argillic horizon and the overall soil fertility level. The rainfall regime during the experimental period included years with drought, normal rainfall, and a very wet year.Tied-ridging enhanced the response to rainfall and fertilizer, the soil supply of plant available N, the positive effect of inter-cropping on total grain yield, and the harvest index. The combined response to annual rainfall and, N and P fertilizer under tied-ridged conditions could be summarised as simple empirical functions accounting for 98% of the variance in yields. Considerable yield increases above "farmers' practices" (i.e. flat cultivation and no fertilizer) could be realised by combining tied-ridged tillage with inputs of mineral N and P fertilizer, reaching maize grain yield levels of six times the prevailing yield under farmers' practices of approximate 1 Mg ha(-1). Similarly, the rainfall-grain productivity could be tripled reaching levels of 6 kg ha(-1) mm(-1) at high fertilizer inputs in years of near-normal rainfall. The effect of tied-ridging was both positive and negative, with the positive effect dominating at near-normal rainfall (500-600 mm) whereas the negative effect dominated at annual rainfalls above 700-900 mm. However, the negative effect could be partly mitigated through fertilizer inputs. The site with the more weathered soil displayed a higher sensitivity to moisture deficits and excesses and a narrower rainfall range with positive effect of ridging. Under near-normal to slightly dry rainfall conditions, tied-ridging without nutrient inputs resulted on an average in 34 and 42% grain yield increase at the two sites.A benefit-cost analysis supports tied-ridging as a potentially profitable technology, especially at the site with better soil quality, slightly higher rainfall and market integration. Thus, a subsistence oriented household will maximise profitability of a maize-cowpea inter-cropping system by using tied-ridging and no fertilizer input whereas a market oriented more resourceful household will maximise profitability from a combination of tied-ridging and high fertilizer inputs. The scarcity of cattle manure and the total cost of application are prohibitive to cattle manure becoming a viable and significant option of nutrient inputs for most farmers in the area. Inter-cropping with cowpea is an important economic factor, currently constrained by diseases and low crop densities.The study highlights the importance of analysing soil and water conservation technologies within a farming systems perspective, and supports a focus on soil and water conservation practices such as tied-ridging in a semi-arid environment with annual rainfall of 500-700 mm. However, recognising potential drawbacks of the tied-ridged technology, it is proposed also to investigate alternative practices improving in situ moisture conservation at minimum soil disturbance. (C) 2002 Elsevier Science B.V. All rights reserved.