For precision agriculture to provide both economic and environmental benefits over conventional farm practice, management strategies must be developed to accommodate the spatial variability in crop performance that occurs within fields. Experiments were established in crops of winter barley (Hordeum vulgare L.) over three seasons. The aim of which was to evaluate a set of variable rate nitrogen strategies and examining the spatial variation in crop response to applied N. The optimum N application rate varied from 90 to in excess of 160 kg [N] ha−1 in different parts of the field, which supports the case for applying spatially variable rates of N. This, however, is highly dependent on seasonal variations, e.g. the quantity and distribution of rainfall and the effect that this has on soil moisture deficits and crop growth. Estimates of yield potential, produced from either historic yield data or shoot density maps derived from airborne digital photographic images, were used to divide experimental strips into management zones. These zones were then managed according to two N application strategies. The results from the historic yield approach, based on 3 yr of yield data, were inconsistent, and it was concluded that that this approach, which is currently the most practical commercial system, does not provide a suitable basis for varying N rates. The shoot density approach, however, offered considerably greater potential as it takes account of variation in the current crop. Using this approach, it was found that applying additional N to areas with a low shoot population and reducing N to areas with a high shoot population resulted in an average strategy benefit of up to 0·36 t ha−1 compared with standard farm practice.
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机译:为了使精密农业能够提供比常规农业实践更多的经济和环境效益,必须制定管理策略以适应田间作物生长的空间变异性。在三个季节的冬季大麦(Hordeum vulgare L.)作物中建立了实验。其目的是评估一套可变速率的氮肥策略,并研究作物对施用氮素的反应的空间变化。最佳氮肥施用量从90公斤到160公斤[N] ha-1以上不等。该字段支持应用N的空间变化率的情况。但是,这在很大程度上取决于季节性变化,例如降雨的数量和分布及其对土壤水分不足和作物生长的影响。根据历史产量数据或机载数字摄影图像得出的枝条密度图得出的潜在产量估算值可用于将实验条划分为管理区。然后根据两个N应用策略管理这些区域。历史的产量法基于3年的产量数据得出的结果不一致,因此得出的结论是,该方法是目前最实用的商业系统,不能为改变氮含量提供合适的基础。然而,由于考虑到当前作物的变化,枝条密度法提供了更大的潜力。使用这种方法,发现与标准的农场做法相比,向低芽种群的区域施用额外的氮,而向高芽种群的区域减少氮,导致平均策略收益高达0·36 t ha-1。
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