Manure is used as a source of nutrients and organic matter for agricultural lands, but its unbalanced use has unfortunately made nitrogen (N) and phosphorous (P) leakage to the environment quite common in Western Europe. One way to optimize the use of manure is variable rate (VR) application, wherein within field spatial variability of soil nutrient provision is accounted for. This work evaluated the economic and environmental benefits of a P-based VR manure application and compared it to an N-based uniform rate (UR) application. An on-line visible and near-infrared spectroscopy sensor was used to collect on-line spectral data from soils in two fields of 7.9 and 5.1 ha with barley and wheat, respectively, in Belgium. A calibration model to predict extractable P (P) in soil was developed by partial least squares regression. Based on the locally predicted P level, the P-fertilizer application rate was calculated. According to P₂O₅ content in manure, manure application rates were set based on the level of soil P measured with the on-line soil sensor. Based on application maps, a strip experiment was conducted to compare the efficiency of VR and UR treatments. The results showed that P-based VR manure application resulted in almost the same yield as the UR treatment; however, it saved the environment by reducing N by 44 kg/ha and 29 kg/ha, and P₂O₅ by 18 kg/ha and 12 kg/ha, when applied in the two fields. Since farmers received compensation from the manure providers for allowing the manure to be applied in their fields, the P-based VR manure application using less manure has resulted in a smaller gross margin than the N-based UR method, by which more manure was applied. However, if farmers had to pay for this application (as is the case in some European countries), a P-based VR manure application would result in positive gross margins. It is encouraged to adopt VR manure applications in arable crop production, as both economic and environmental benefits are feasible.

粪肥被用作农田养分和有机物的来源，但不幸的是，其使用不平衡导致氮 (N) 和磷 (P) 泄漏到环境中在西欧相当普遍。优化粪肥使用的一种方法是可变速率（VR）施用，其中考虑了田间土壤养分供应的空间变异性。这项工作评估了基于 P 的 VR 肥料施用的经济和环境效益，并将其与基于 N 的统一施肥量 (UR) 施用进行了比较。使用在线可见光和近红外光谱传感器收集比利时两块面积分别为 7.9 公顷和 5.1 公顷的大麦和小麦田​​地的土壤在线光谱数据。通过偏最小二乘回归开发了预测土壤中可提取磷 (P) 的校准模型。根据当地预测的磷水平，计算磷肥施用量。根据粪便中P ₂ O ₅含量，根据在线土壤传感器测量的土壤P水平设定粪便施用量。根据应用图，进行条带实验来比较 VR 和 UR 治疗的效率。结果表明，施用基于磷的 VR 肥料与 UR 处理的产量几乎相同；然而，当应用于这两个田地时，它可以将氮减少 44 公斤/公顷和 29 公斤/公顷，将 P ₂ O ₅减少 18 公斤/公顷和 12 公斤/公顷，从而保护了环境。由于农民因允许在田间施用粪肥而从粪肥供应商处获得补偿，因此使用较少粪肥的基于 P 的 VR 粪肥施用导致毛利率低于施用更多粪肥的基于 N 的 UR 方法。然而，如果农民必须为这种应用付费（就像一些欧洲国家的情况），基于 P 的 VR 肥料应用将带来正的毛利率。鼓励在耕种作物生产中采用VR肥料施用，因为经济效益和环境效益都是可行的。