Optical crop sensor for variable-rate nitrogen fertilization in corn: II - indices of fertilizer efficiency and corn yield

Abstract

SUMMARYGenerally, in tropical and subtropical agroecosystems, the efficiency of nitrogen (N) fertilization is low, inducing a temporal variability of crop yield, economic losses, and environmental impacts. Variable-rate N fertilization (VRF), based on optical spectrometry crop sensors, could increase the N use efficiency (NUE). The objective of this study was to evaluate the corn grain yield and N fertilization efficiency under VRF determined by an optical sensor in comparison to the traditional single-application N fertilization (TSF). With this purpose, three experiments with no-tillage corn were carried out in the 2008/09 and 2010/11 growing seasons on a Hapludox in South Brazil, in a completely randomized design, at three different sites that were analyzed separately. The following crop properties were evaluated: aboveground dry matter production and quantity of N uptake at corn flowering, grain yield, and vegetation index determined by an N-Sensor ® ALS optical sensor. Across the sites, the corn N fertilizer had a positive effect on corn N uptake, resulting in increased corn dry matter and grain yield. However, N fertilization induced lower increases of corn grain yield at site 2, where there was a severe drought during the growing period. The VRF defined by the optical crop sensor increased the apparent N recovery (NRE) and agronomic efficiency of N (NAE) compared to the traditional fertilizer strategy. In the average of sites 1 and 3, which were not affected by (1)

A Sustainability Assessment of the Greenseeker N Management Tool: A Lysimetric Experiment on Barley

“…Some studies evaluated the economic aspect, revealing savings in same cases [23,24] and poor economic performances in others due to reduced N rates that often affect yield [25]. Some studies focused on evaluating the productivity aspect, finding yield increase [26], no effect [27], or variable results [28]. Finally, other studies focused on evaluating the environmental aspects of adopting variable rate technologies, revealing an impact reduction in some cases [29][30][31][32] and no effect in others [33].…”

Adoção E Uso Da Agricultura De Precisão Na Região Das Missões Do Rio Grande Do Sul

“…Atualmente, no Brasil e no RS, existem pesquisas relacionadas com AP no que diz respeito à compactação do solo (Girardello et al, 2014a), tráfego controlado (Girardello et al, 2014b), manejo de pastagens e culturas de grãos (SILVA et al, 2014), sensores de adubação nitrogenada (Bragagnolo et al, 2013), zonas de manejo, fertilidade do solo Demattê et al, 2014), entre outras, sendo consideradas bem desenvolvidas as pesquisas que envolvem solo e seus manejos, porém são poucos os estudos na área de defesa fitossanitária. Dessa forma, as ferramentas da AP devem ser consideradas como um importante auxílio no manejo de lavouras (Ferraz et al, 2011).…”

“…A adoção de tecnologias que busquem a sustentabilidade da atividade agrícola é bem--vinda. Neste aspecto, a AP busca extrair o máximo de produtividade sem agressão do meio, ao mesmo tempo em que reduz o risco de impacto ambiental (Hong et al, 2007;Bragagnolo et al, 2013).…”

A Review of Practice and Implementation of the Internet of Things (IoT) for Smallholder Agriculture

“…In another common application, optical sensors attached to fertilizer equipment measure the light reflectance at specific wavebands, which are related to chlorophyll content, an indicator of plant nitrogen (N) content, and fertilizer is applied in that location based on the estimated N deficiency. Compared to the grower selected constant-rate, sensor-enabled variable-rate fertilization has been shown to increase corn N uptake by more than 20% [9] and save 10-15 kg N per acre of corn and cotton, especially when soil N content varies year-to-year [10].…”