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Title:Agronomic and nutritional considerations for increased soybean productivity
Author(s):Bender, Ross Randall
Director of Research:Below, Frederick E.
Doctoral Committee Chair(s):Below, Frederick E.
Doctoral Committee Member(s):Bradley, Carl A.; Mulvaney, Richard L.; Nafziger, Emerson D.
Department / Program:Crop Sciences
Discipline:Crop Sciences
Degree Granting Institution:University of Illinois at Urbana-Champaign
Degree:Ph.D.
Genre:Dissertation
Subject(s):soybean
nutrient uptake
agronomic management
productivity
irrigation
Abstract:Increasing soybean [Glycine max (L.) Merr.] productivity will require a comprehensive understanding of the agronomic, nutritional, and genetic factors that influence soybean yield. Despite recent agricultural innovations, there is a common perception that soybean yields have reached a plateau. While most producers overlook the fertility needs of soybean, others believe that improved nutritional management may hold promise for improving soybean productivity. The synergy between adequate nutrient availability in combination with complementary agronomic practices, may be necessary to realize the genetic yield potential of soybean. For these reasons, the objective of this research was to quantify how agronomic and nutritional management practices can be employed to improve soybean productivity which encompasses four research areas: What are the nutritional needs of current soybean cultivars which frequently realize higher yields now than ever before? Research was conducted to quantify the macro- and micronutrient needs of modern soybean cultivars. Nutrients exhibited variation in their uptake, partitioning, and remobilization and presented data should be considered relevant for producers who target or achieve a yield level of 3500 kg ha-1 or higher. Current soybean varieties also exhibited greater dry weight harvest index values relative to previous research which has concomitantly influenced the rate, duration, and partitioning of nutrient accumulation in soybean. Collectively, these findings emphasize the importance of season-long nutrient availability to most effectively meet soybean fertility needs. Can management practices be designed to supply these nutritional needs and achieve improved soybean productivity? Quantification of soybean fertility needs highlighted the importance of phosphate availability, and when supplied as one of five categorical management factors, significant yield increases were realized. Other factors including variety selection, seed treatment, foliar fungicide and insecticide use, and row spacing configuration contributed to improved soybean productivity across a range of environments. An additional study provided in-season applications of N, K, and S using a subsurface drip irrigation (SDI) system and improved seed yield by as much as 357 kg ha-1. Do other agronomic decisions such as variety selection influence the responsiveness to nutrient supply? Results indicated that variety selection significantly influences the outcome of nutritional and agronomic treatments. The value of fertilization, foliar fungicide and insecticide, and seed treatment practices were as much as two-fold greater when applied to fuller season varieties. Additional findings determined that varietal selection cannot be based on RM alone and that classifying varieties based on their responsiveness to nutrient supply was predictive of their response to supplemental agronomic management. What physiological basis exists to support these management-induced productivity improvements? Soybean’s indeterminate growth habit and compensatory nature between yield components emphasize the complexity of yield determination in soybean. As a result, a more thorough understanding of seed number and seed mass establishment was conducted within the canopy to identify how source and/or sink related factors may limit yield. Fertilization and foliar leaf protection treatments significantly improved yield through different, canopy-dependent, yield component strategies. Responses differed among cultivars which underscore the importance of variety selection and agronomic management as a concerted effort for improved soybean productivity.
Issue Date:2015-04-20
Type:Thesis
URI:http://hdl.handle.net/2142/78727
Rights Information:Copyright 2015 Ross Bender
Date Available in IDEALS:2015-07-22
Date Deposited:May 2015


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