Corn Irrigation and Fertilizer Use BMPs versus Conventional Growing Practices, aTwo-Year Overview

摘要

Can fertilizer be reduced and irrigation scheduling be optimized in corn production without reducing yield? The answer to this question has been studied during 2015 and 2016 on sandy soils in the Suwanee River, Florida region. Due to karst topography,rapid water flow and absence of a natural filtration system, an increased vulnerability to groundwater pollution characterizes this area. Thus, excess nitrogen (N) fertilizer applied with the intention of obtaining higher yields, is a potential threat to waterbodies. The main objective was to improve irrigation and fertilizer Best Management Practices (BMPs) compared to conventional practices. Five irrigation treatments determined irrigation by: (i) GROW, mimicking grower's practices, (ii) SWB, using atheoretical soil water balance, (iii) SMS, monitoring volumetric water content measured by soil moisture sensors and triggered using maximum allowable depletion (MAD) and field capacity (FC) as thresholds to refill the soil profile, (iv) Reduced: irrigation (60% of GROW) representing a low irrigation treatment and (v) NON: non-irrigated plots. Three fertility rates: Fl=300, F2=220 and F3=140 lb N/ac were evaluated. The experimental design consisted of a randomized complete block arranged in a split plot with four replicates. During 2015, yield was not significantly different across irrigated treatments (GROW, SMS and Reduced: 193,191 and 201 bu/ac); however, the non-irrigated treatment had significantly lower yield than all other treatments except SWB(SWB and NON: 178 and 143 bu/ac, respectively). Fertility rates 300 and 220 lb N/ac (196 and 180 bu/ac), or 220 and 140 lb N/ac were not significantly different (180 and 168 bu/ac); however, the 300 lb N/ac treatment was significantly higher than 140 lbN/ac (196 bu/ac vs. 168 bu/ac, respectively). In 2016, no significant differences in yield were found among irrigated treatments, except versus the NON treatment which had significantly lower yield (GROW, SWB, SMS and Reduced: 202, 184,188,191 bu/ac vs.non: 127 bu/ac). Fertility treatments did not differ statistically (Fl, F2 and F3: 183,180 and 173 bu/ac). Irrigation and fertilizer were reduced without reducing yield by using BMPs compared to conventional practices during the first two years of research.