ABSTRACT

Currently, most rice farmers in the central highlands of Madagascar do not apply mineral fertilizer in their fields and we investigated whether a fertilizer micro-dose applied to the seedling nursery could serve as an entry point for intensification. Effects of nursery applications of a micro-dose of mineral (P and NPK) or locally produced sources of fertilizers (Guanomad, Vermicompost) on seedling vigour were evaluated, as was final grain yield after transplanting to main fields that were either not fertilized (farmers’ practice) or received combinations of mineral N, P and K fertilizer. Applying only P to the nursery had minor effects and we conclude that early seedling vigor is more limited by N than P, while grain yield in the main field was more limited by P than N. Carry-over effects of the nursery application of NPK and of guano on final grain yield were observed under farmers’ practice and when only urea was applied. The nursery NPK application significantly increased agronomic nitrogen use efficiency of urea application. We conclude that the low cost of micro-dosing NPK in the nursery makes this a profitable option for small-scale farmers cultivating rice on poor-fertility soils. Sole urea application in the main field is not a profitable option but would at least need additional nursery NPK application as an insurance against losing investments in N fertilization. Longer-term sustainability would require direct nutrient inputs into the main plot and additional low-cost nutrient management options should therefore be considered.

摘要

目前，马达加斯加中部高地的大多数稻农在他们的田地中都没有施用矿物肥料，我们调查了在苗圃中施用的微量肥料是否可以作为集约化的切入点。评估了苗圃施用微量矿物质（磷和氮磷钾）或当地生产的化肥（瓜诺马德，Ver米科珀特）对幼苗活力的影响，并评估了移植到未施肥的主要田间（农民）的最终谷物产量'实践）或接收到的氮，磷和钾矿物肥料的组合。仅对苗圃施用磷对苗木的影响不大，我们得出的结论是，早期幼苗活力受氮的影响大于磷，而主田的谷物产量受磷的影响大于氮。在农民的实践中，当只施用尿素时，观察到了苗圃施用NPK和鸟粪对最终谷物产量的残留效应。苗圃氮磷钾施用显着提高了尿素施用对农艺氮的利用效率。我们得出的结论是，苗圃中微剂量NPK的低成本使其成为在贫瘠土壤上种植水稻的小规模农民的一项有利可图的选择。在主要领域单独施用尿素不是一种有利可图的选择，但至少需要额外的苗圃NPK施用，以防止氮肥投资损失。长期可持续性将需要直接向主要地块输入养分，因此应考虑采用其他低成本养分管理方案。苗圃氮磷钾施用显着提高了尿素施用对农艺氮的利用效率。我们得出的结论是，苗圃中微剂量NPK的低成本使其成为在贫瘠土壤上种植水稻的小规模农民的一项有利可图的选择。在主要领域单独施用尿素不是一种有利可图的选择，但至少需要额外的苗圃NPK施用，以防止氮肥投资损失。长期可持续性将需要直接向主要地块输入养分，因此应考虑采用其他低成本养分管理方案。苗圃氮磷钾施用显着提高了尿素施用对农艺氮的利用效率。我们得出的结论是，苗圃中微剂量NPK的低成本使其成为在贫瘠土壤上种植水稻的小规模农民的一项有利可图的选择。在主要领域单独施用尿素不是一种有利可图的选择，但至少需要额外的苗圃NPK施用，以防止氮肥投资损失。长期可持续性将需要直接向主要地块输入养分，因此应考虑采用其他低成本养分管理方案。我们得出的结论是，苗圃中微剂量NPK的低成本使其成为在贫瘠土壤上种植水稻的小规模农民的一项有利可图的选择。在主要领域单独施用尿素不是一种有利可图的选择，但至少需要额外的苗圃NPK施用，以防止氮肥投资损失。长期可持续性将需要直接向主要地块输入养分，因此应考虑采用其他低成本养分管理方案。我们得出的结论是，苗圃中微剂量NPK的低成本使其成为在贫瘠土壤上种植水稻的小规模农民的一项有利可图的选择。在主要领域单独施用尿素不是一种有利可图的选择，但至少需要额外的苗圃NPK施用，以防止氮肥投资损失。长期可持续性将需要直接向主要地块输入养分，因此应考虑采用其他低成本养分管理方案。