Nitrogen Application to Soybean at Early Reproductive Development

Abstract

tion and nodulation, thus reducing N 2 fixation capacity (Shibles, 1998). Application of N before planting or dur-Nitrogen application during soybean [Glycine max (L.) Merrill] ing the early growth stages can suppress the N 2 fixation reproductive stages has the potential to increase soybean productivity. The objective of this study was to determine the impact of N fertilizer process. Fertilizer N applied during soybean reproducapplied to the soil at the beginning pod growth stage on soybean yield tive stages (R1 to R5) might increase the capacity and and grain quality. Additional objectives were to study alternative N duration of the inorganic N utilization period while mainfertilizer and application practices that might enhance soybean use taining N 2 fixation. of applied N. A field study was conducted at five locations in Iowa A study conducted in Kansas with irrigated soybean during 1999 and 2000. Nitrogen treatments were urea and polymerfound significant soybean yield response when N was coated urea broadcast and subsurface band placed between the rows applied between the R3 and full pod stage (R4) (Wesley at 45 and 90 kg N ha Ϫ1 and a no-N control. The study showed few, et al., 1998). Their work showed an average yield insmall, and inconsistent effects of N material, placement, and rate on crease of 464 kg ha Ϫ1 at six of eight sites. The two grain yield and quality components at individual sites or when comnonresponsive sites had low yield, below 3360 kg ha Ϫ1 . bined across individual sites. There were no significant effects on grain yield, with only a 39 kg ha Ϫ1 increase from applied N. Grain protein, oil, Nitrogen application did not enhance grain protein and and fiber concentrations were the same with or without N application.oil. This study suggests that in soybean with high yield Aboveground plant dry matter (DM) at the R6 growth stage was potential (3700 kg ha Ϫ1 or greater), 22 kg N ha Ϫ1 would greater with the higher N rate, but plant DM with N application was produced a positive yield response. Gascho (1993) in lower than the no-N control. Nitrogen concentration in plant DM Georgia studied a variety of N application treatments was significantly increased with applied N. In conclusion, N application Published in Agron. J. 97: 615-619 (2005).

Plant density and mineral nitrogen fertilization influencing yield, yield components and concentration of oil and protein in soybean grains

“…According to Bellaloui et al (2015), an increment of plant density promoted an increase in the protein concentration of soybean grains, which was not observed in the present study. In the same way, Boroomandam et al (2009) The use of mineral N did not influence grain yield in the two growing seasons (Tables 3,4).…”

Nitrogen Sources and Rates Affect Soybean Seed Composition in Mississippi

“…Climatic conditions such as lower temperatures and higher precipitation amounts during seed filling may reduce protein and oil concentration, whereas high air temperatures and moderate rainfall at the seed filling period can result in higher protein concentration in soybean seeds [35,38]. In general, N sources performed similarly and did not show differences for most of the seed composition parameters measured in our study, in agreement with findings from other studies [15]. McCoy (2016) reported that belowground biomass, root length, root area, root diameter and nodule numbers were significantly lower for clay soil compared to silt-loam soil, which possibly affected biological nitrogen fixation and consequently, soybean response to N fertilizer applications [19].…”

“…Previous studies have shown that protein and oil concentrations were negatively correlated resulting in the opposite trend for soybean seed protein and oil concentration in response to N applications in our study on clay soil [16]. In agreement with our results, multiple studies have also reported inconsistent responses of soybean seed protein and oil content to N applications [10,15,16,[39][40][41][42]. In Arkansas, 112 kg N ha −1 when applied at the R2 growth stage in soybeans caused no changes in seed protein and oil concentration compared to unfertilized soybeans on silt loam soil [40].…”

“…Seed fiber content, ADF and NDF were affected by N rate only on silt loam soil. Barker and Sawyer (2005) found that fiber concentration in soybean seeds remained unchanged when N was applied at 45 and 90 kg ha −1 during reproductive stages [15].…”

“…In an effort to provide soybeans with adequate N for maximum seed yield, producers have considered applying N fertilizer to their soybean crop. Previous studies have reported inconsistent responses of soybean seed yield to N fertilizer applications [6][7][8][9][10][11][12][13][14][15][16][17][18]. For instance, in the Southern US, no effect was reported in Texas [7] and Alabama [6].…”