Sharma Lakesh K, Bali Sukhwinder K, Dwyer James D, Plant Andrew B, Bhowmik Arnab
Department of Cooperative Extension, University of Maine, 57 Houlton Rd, Presque Isle, ME 04769, USA.
Maine Potato Board, 744 Main Street, Suite 1, Presque Isle, ME 04769, USA.
Sensors (Basel). 2017 May 11;17(5):1095. doi: 10.3390/s17051095.
In Maine, potato yield is consistent, 38 t·ha, for last 10 years except 2016 (44 t·ha) which confirms that increasing the yield and quality of potatoes with current fertilization practices is difficult; hence, new or improvised agronomic methods are needed to meet with producers and industry requirements. Normalized difference vegetative index (NDVI) sensors have shown promise in regulating N as an in season application; however, using late N may stretch out the maturation stage. The purpose of the research was to test Trimble GreenSeeker (TGS) and Holland Scientific Crop Circle™ ACS-430 (HCCACS-430) wavebands to predict potato yield, before the second hilling (6-8 leaf stage). Ammonium sulfate, S containing N fertilizer, is not advised to be applied on acidic soils but accounts for 60-70% fertilizer in Maine's acidic soils; therefore, sensors are used on sulfur deficient site to produce sensor-bound S application guidelines before recommending non-S-bearing N sources. Two study sites investigated for this research include an S deficient site and a regular spot with two kinds of soils. Six N treatments, with both calcium ammonium nitrate and ammonium nitrate, under a randomized complete block design with four replications, were applied at planting. NDVI readings from both sensors were obtained at V8 leaf stages (8 leaf per plant) before the second hilling. Both sensors predict N and S deficiencies with a strong interaction with an average coefficient of correlation (²) ~45. However, HCCACS-430 was observed to be more virtuous than TGS. The correlation between NDVI (from both sensors) and the potato yield improved using proprietor-proxy leaf area index (PPLAI) from HCCACS-430, e.g., ² value of TGS at Easton site improve from 48 to 60. Weather data affected marketable potato yield (MPY) significantly from south to north in Maine, especially precipitation variations that could be employed in the N recommendations at planting and in season application. This case study addresses a substantial need to revise potato N recommendations at planting and develop possible in season N recommendation using ground based active optical (GBAO) sensors.
在缅因州，除2016年（44吨/公顷）外，过去10年马铃薯产量一直稳定在38吨/公顷，这证实了采用当前施肥方法提高马铃薯产量和质量很困难；因此，需要新的或改进的农艺方法来满足生产者和行业的需求。归一化植被指数（NDVI）传感器在作为季内追肥调节氮肥用量方面显示出前景；然而，后期施氮可能会延长成熟期。本研究的目的是在第二次培土（6-8叶期）前，测试天宝GreenSeeker（TGS）和荷兰科学作物圈™ ACS-430（HCCACS-430）波段预测马铃薯产量的能力。硫酸铵这种含硫氮肥，不建议施用于酸性土壤，但在缅因州的酸性土壤中占化肥用量的60-70%；因此，在缺硫地块使用传感器，以便在推荐不含硫的氮源之前制定与传感器结合的硫施用指南。本研究调查的两个试验地点包括一个缺硫地块和一个有两种土壤类型的常规地块。种植时采用随机完全区组设计，设置6种氮处理，包括硝酸钙铵和硝酸铵，重复4次。在第二次培土前的V8叶期（每株8片叶）获取两个传感器的NDVI读数。两个传感器都能预测氮和硫缺乏情况，且相互作用强烈，平均相关系数（²）约为45。然而，观察发现HCCACS-430比TGS表现更优。利用HCCACS-430的所有者代理叶面积指数（PPLAI），NDVI（来自两个传感器）与马铃薯产量之间的相关性得到了提高，例如，伊斯顿试验点TGS的²值从48提高到了60。气象数据对缅因州从南到北的适销马铃薯产量（MPY）有显著影响，特别是降水变化，可用于种植时和季内追肥的氮肥推荐。本案例研究满足了大幅修订种植时马铃薯氮肥推荐量以及利用地面有源光学（GBAO）传感器制定可能的季内氮肥推荐量的迫切需求。
