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Title:A meta-analysis of how management practices affect soybean yield and quality
Author(s):Rampazzo Favoretto, Vitor
Advisor(s):Below, Frederick E
Contributor(s):Butts-Wilmsmeyer, Carrie; Diers, Brian
Department / Program:Crop Sciences
Discipline:Crop Sciences
Degree Granting Institution:University of Illinois at Urbana-Champaign
Soybean quality
Abstract:Soybean [Glycine max (L.) Merr.] is a major cultivated crop, providing protein and oil for human and animal feed. While soybean yields in the United States have increased over the years, grain oil concentrations have remained relatively constant while protein concentrations have decreased. The objective of this work was to determine if management practices (nitrogen (N), phosphorus (P), and potassium (K)) fertilization; foliar protection, and reduced row spacing) could simultaneously increase yield as well as seed protein and oil concentrations. A meta-analysis was performed on 50 soybean crop management projects conducted between 2012 and 2018, which included five field sites around Illinois. These trials measured yield, seed protein and oil concentrations, weather (precipitation and temperature), soil constituents (CEC, organic matter, P and K levels), and recorded planting and harvest dates. A meta-analysis of the mean differences was used to examine the impact of management practices on yield, and moderators to explain the heterogeneity levels between studies were included. Nitrogen or P fertilization, reduced row spacing and foliar protection all increased yield, while K fertilization tended to decrease yield. Seed protein concentration was not affected by N or K fertilization, but was altered by P fertilization depending on the method of application. Seed protein concentration decreased when the P fertilizer was banded beneath the crop row, but tended to increase when the P fertilizer was broadcasted on the soil surface. Reduced row spacing and foliar protection decreased seed protein concentration. Banded P fertilization, reduced row spacing, and foliar protection all increased seed oil concentration. Soil organic matter level and planting date were moderators that explained the variation in the responses to N fertilization of soybean yield and protein concentration, respectively. In regards to P fertilization, soil P level was a moderator of the yield response, while soil CEC was a moderator of the seed oil concentration response. Yield and seed quality responses to reduced row spacing were both moderated by soil CEC. In response to foliar protection, yield was moderated by soil organic matter, while seed protein and oil concentrations both had location as a moderator. These data show that N and P fertilization, reduced row spacing, and foliar protection can individually increase soybean yield, and that banded P fertilization, reduced row spacing and foliar protection can increase seed oil concentration, but no management practice evaluated in this review was able to simultaneously increase yield and seed protein concentration.
Issue Date:2019-12-12
Rights Information:Copyright 2019 Vitor Rampazzo Favoretto
Date Available in IDEALS:2020-03-02
Date Deposited:2019-12

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