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首页> 外文学位 >Conservation agriculture practices in rain-fed smallholder farming systems of western Kenya and western Nebraska: Soil nutrient cycling, greenhouse gas fluxes and crop productivity.
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Conservation agriculture practices in rain-fed smallholder farming systems of western Kenya and western Nebraska: Soil nutrient cycling, greenhouse gas fluxes and crop productivity.

机译：肯尼亚西部和内布拉斯加西部的雨养小农耕作系统中的保护性农业做法：土壤养分循环，温室气体通量和作物生产力。

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摘要

Conservation Agriculture (CA) encompasses a set of practices designed to improve crop yields and soil quality. In Kenya, CA is gaining acceptance not as an alternative, but rather necessity to increase food production by food insecure smallholder farmers. Limited understanding of short-term agroecosystem response during transition to CA can impede adoption. In Nebraska, CA can benefit dryland winter wheat producers by offsetting negative consequences of increased climate variability. This dissertation combines two research projects that explore two aspects of CA. It explores short-term impacts of selected CA practices on soil nitrogen (N), greenhouse gas (GHG) fluxes, weed population dynamics and crop performance at low altitude with two annual cropping seasons and high altitude with one annual cropping season in western Kenya. Three tillage practices (conventional, minimum and no-till) were combined with three cropping systems (continuous maize intercropped with common beans; maize intercropped with common beans relayed with mucuna cover crop after beans harvest; and maize, common beans and mucuna planted in strip cropping arrangement). In general, low elevation region experienced high GHG fluxes, soil N mineralization but significantly lower yields compared with the high elevation region. Transitioning to not-till or reduced-till-based CA practices or forgoing second-season cropping will reduce soil disturbance and C and N losses due to mineralization and GHG emissions. Even though evidence of early accrual of soil benefits associated with CA practices may take longer than the timeframe of this research, farmers notice immediate reduction in weed competition, which is one of the leading causes of yield loss in Kenya. The second part of this dissertation discusses the effects of tillage-based CA systems on winter wheat yields, soil N and phosphorus in winter wheat/summer crop/fallow rotations in western Nebraska. Treatments included organic and reduced tillage with sunflower as a summer crop and reduced tillage and no-till rotations with millet as a summer crop. Results suggested that no-till improved soil N but reduced wheat yield. Including sunflowers in the rotation resulted in a decline in plant available soil water and increased N mineralization, which may negatively affect crop performance during periods of drought.
机译：保护性农业（CA）包含一系列旨在提高农作物产量和土壤质量的实践。在肯尼亚，CA的认可不是替代方案，而是增加粮食不安全的小农户增加粮食产量的必要性。过渡到CA期间对短期农业生态系统反应的了解有限，可能会阻碍采用。在内布拉斯加州，加利福尼亚州可以抵消气候变化加剧带来的负面影响，从而使旱地冬小麦生产者受益。本文结合两个研究项目，探讨了CA的两个方面。它探讨了肯尼亚西部某些低海拔地区（每年种植一个季节）和低海拔（一年种植一个季节）对某些氮肥对土壤氮（N），温室气体（GHG）通量，杂草种群动态和作物生长的短期影响。将三种耕作方式（常规，最少和免耕）与三种种植系统（连续玉米与普通豆间作；玉米与普通豆间种并用豆科覆盖的农作物覆盖）；以及玉米，普通豆和木豆分条种植种植安排）。通常，与高海拔地区相比，低海拔地区的温室气体通量高，土壤氮矿化程度高，但单产却低得多。过渡到免耕或减耕的CA做法或放弃第二季种植，将减少土壤干扰以及由于矿化和温室气体排放而造成的碳和氮损失。尽管与CA做法相关的土壤效益的早期累积证据可能需要比本研究的时间更长的时间，但农民仍注意到杂草竞争的立即减少，这是肯尼亚产量损失的主要原因之一。本文的第二部分讨论了耕作型CA系统对内布拉斯加州西部冬小麦/夏季作物/休耕轮作的冬小麦产量，土壤氮和磷的影响。处理方法包括有机耕作和减少耕作，以向日葵作为夏季作物，减少耕作和免耕轮作，作为夏季作物。结果表明，免耕可改善土壤氮素，但小麦产量下降。在轮作中包括向日葵会导致植物可用土壤水量减少和氮矿化增加，这可能在干旱期间对作物生长产生负面影响。

著录项

  • 作者

    Odhiambo, Judith Achieng.;

  • 作者单位

    University of Wyoming.;

  • 授予单位 University of Wyoming.;
  • 学科 Agriculture Agronomy.
  • 学位 Ph.D.
  • 年度 2014
  • 页码 214 p.
  • 总页数 214
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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