Improving in-season nitrogen recommendations for maize using an active sensor
Improving in-season nitrogen recommendations for maize using an active sensor
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DOI：
10.1016/j.fcr.2010.09.005
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发表时间：
2011-01
影响因子：
5.8
通讯作者：
J. Schmidt;Doug B. Beegle;Q. Zhu;R. P. Sripada
中科院分区：
文献类型：
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作者：
J. Schmidt;Doug B. Beegle;Q. Zhu;R. P. Sripada
主动作物冠层反射传感器可用于提高玉米(Zea Mays L.)的氮素利用效率，如果土壤氮素有效性和植物需要量的时间和空间变异性在季节性施氮中得到了充分的解释。我们的目标是评估使用主动冠层传感器制定玉米氮素推荐的成功。这项研究于2007年至2009年在美国宾夕法尼亚州东部、中部和东南部的21个农民田里进行，代表了玉米产区。每处设4个小区，设7个施氮量(0~280kgnha−1)和1个施氮量(280kgnha−1)。在第6~7叶生长期(V6~V7)采集冠层在590 nm和880 nm波段的反射率、土壤样品、叶绿素仪和地上生物量。根据从零侧植到280kgnha−1at种植处理的相对测量，确定了相对琥珀归一化植被指数(ANDVI Relative)和相对SPAD(SPAD Relative)。本研究的观察结果与经济最佳氮肥用量(EONR)和由先前研究发展而来的VI相对、前导NO3检验(PSNT)或SPAD相对之间的关系进行了比较。这些比较是基于观察到的EONR和先前确定的预测关系之间的绝对平均差(AMD)。本研究中EONR与ANVI关系的AMD值为46kgnha−1。PnT(AMD值=66kgnha−1)和SPADRelative值(AMD值=72kgnha−1)均不能作为EONR的良好指标。当使用两个研究的所有观察结果来分析EONR与各种测量之间的关系时，ANDVI Relative(R2=0.65)提供了比PSNT(R2=0.49)或SPADRelative(不显著)更好的EONR估计。作物反射率捕捉到了与PSNT和SPADRelative类似的信息，这反映在这些变量之间的强烈关系(R2>；0.60)中。使用主动传感器(即ANDVIRelative)的作物冠层反射率比PSNT或SPADRelative提供了更好或更好的EONR指标，并提供了在空间上轻松调整季节性氮肥施用量的机会。
An active crop canopy reflectance sensor could be used to increase N-use efficiency in maize (Zea mays L.), if temporal and spatial variability in soil N availability and plant demand are adequately accounted for with an in-season N application. Our objective was to evaluate the success of using an active canopy sensor for developing maize N recommendations. This study was conducted in 21 farmers’ fields from 2007 to 2009, representing the maize production regions of east central and southeastern Pennsylvania, USA. Four blocks at each site included seven sidedress N rates (0–280kgNha−1) and one at-planting N rate of 280kgNha−1. Canopy reflectance in the 590nm and 880nm wavelengths, soil samples, chlorophyll meter (SPAD) measurements and above-ground biomass were collected at the 6th–7th-leaf growth stage (V6–V7). Relative amber normalized difference vegetative index (ANDVIrelative) and relative SPAD (SPADrelative) were determined based on the relative measurements from the zero sidedress treatment to the 280kgNha−1at-planting treatment. Observations from the current study were compared to relationships between economic optimum N rate (EONR) and ANDVIrelative, presidedress NO3test (PSNT), or SPADrelativethat were developed from a previous study. These comparisons were based on an absolute mean difference (AMD) between observed EONR and the previously determined predicted relationships. The AMD for the relationship between EONR and ANDVIrelativein the current study was 46kgNha−1. Neither the PSNT (AMD=66kgNha−1) nor the SPADrelative(AMD=72kgNha−1) provided as good an indicator of EONR. When using all the observations from the two studies for the relationships between EONR and the various measurements, ANDVIrelative(R2=0.65) provided a better estimate of EONR than PSNT (R2=0.49) or SPADrelative(not significant). Crop reflectance captured similar information as the PSNT and SPADrelative, as reflected in strong relationships (R2>0.60) among these variables. Crop canopy reflectance using an active sensor (i.e. ANDVIrelative) provided as good or better an indicator of EONR than PSNT or SPADrelative, and provides an opportunity to easily adjust in-season N applications spatially.