Compared to no-till, strip-till can off er improved seedbed conditions and deep banding of fertilizer. Th e objective of this study was to quantify the eff ect of rate and placement of P and K in no-till and strip-till systems on soybean [Glycine max (L.) Merr.] seed yield. A 3-yr fi eld experiment was conducted near Urbana, IL, on Flanagan silt loam (fi ne, smectitic, mesic Aquic Argiudolls) and Drummer silty clay loam (fi ne-silty, mixed, superactive, mesic Typic Endoaquolls) soils, with soybean planted following corn (Zea mays L.). Tillage/fertilizer placement was the main plot with no-till/broadcast (NTBC); no-till/deep band (NTDB); and strip-till/deep band (STDB); deep band placement was 15 cm beneath the planted row. Phosphorus-fertilizer rate (0, 12, 24, and 36 kg P ha -1 yr -1 ) was the subplot, and K-fertilizer rate (0, 42, 84, and 168 kg K ha -1 yr -1 ) was the sub-subplot. Soil water, soil and trifoliate P and K, and seed yield were measured. Overall, STDB produced 3.1 Mg seed ha -1 , 10, and 7% more yield than NTBC and NTDB, respectively. Seed yield, number of pods plant -1 , and trifoliate P concentration and accumulation increased with P fertilization uniformly across tillage/fertilizer placement indicating that fertilization cannot be reduced with deep band applications relative to broadcast applications without a reduction in seed yield, but deep banding increased subsurface soil test levels. Potassium fertilization decreased seed yield in both no-till systems but not in the STDB system. While P and K placement produced no diff erences, improved soybean yield and nutrient accumulation resulted from a tillage eff ect with STDB relative to the no-till systems.

In conservation tillage, fertilizer placement is designed to improve nutrient availability. Our objective was to determine the effect of tillage (no-till and strip-till) and P and K rate and placement on the distribution of soybean [Glycine max (L.) Merr.] roots and on water, P, and K levels in soil. A 3-yr field experiment was conducted near Urbana, IL, with soybean following corn (Zea mays L.). Rates of 0-0, 36-0, 0-168, and 36-168 kg P-K ha"! yr-ŵ ere applied as no-till/broadcast (NTBC), no-till/deep band (15 cm beneath the planted row) (NTDB), and strip-till/deep band (STDB). Roots and soil water, P, and K levels were measured periodically at in-row (IR) and betweenrows (BR) positions at 0-to 5-, 5-to 10-, 10-to 20-, and 20-to 40-cm depths. Deep banding increased P and K soil test levels beneath the row and lowered soil surface test-values compared to broadcast applications, but had no effect on root distribution. Compared to NTBC and NTDB, STDB had a 20% increase in soil water content during the seed-fill period at BR within the top 10 cm of soil where greatest apparent nutrient uptake (estimated by changes in soil-test levels) occurred. Within that zone, NTBC produced and maintained a larger root system than STDB. However, STDB had 23% greater P and 30% greater K accumulation in shoots and also greater apparent nutrient uptake and greater apparent nutrient uptake rate per unit of root surface area. The results indicate that STDB provides overall better soil conditions for P and K uptake compared to the NTBC and NTDB systems.

The economic benefit of using controlled-release N fertilizers on hard red spring wheat (HRSW, Triticum aestivum L.) depends on its cost/price ratio, grain yield, and availability of discount and/or premium prices for protein concentration. The objective of this study was to evaluate the effect of five different proportions (0, 25, 50, 75, and 100%) of polymer-coated urea (PCU) in the N fertilizer mixture applied at three different N rates on (i) HRSW grain yield and protein concentration and (ii) whole-plant dry matter and total N accumulation, and (iii) also to perform an economic analysis. As the proportion of PCU in the fertilizer mixture increased, the grain yield decreased in Environment 1 and remained the same in Environment 2. Cool dry conditions in Environment 1 delayed N release from PCU causing N deficiencies during the critical yield-development phase and resulting in lower grain yield as the PCU proportion increased. In contrast, this was not the case in Environment 2. As the proportion of PCU in the fertilizer mixture increased, protein concentrations increased in both environments indicating that PCU increases soil-N availability later in the growing season, regardless of the early season weather conditions. The proportion of PCU in the fertilizer mixture did not affect total N accumulation and post-harvest soil NO 3 -N concentrations. The results of this study suggest that adding a portion of PCU in the fertilizer mixture can increase HRSW grain protein concentration and provide economic benefits to producers if discount prices are around $20 per Mg or greater.

Discount payments associated with low grain protein concentration in hard red spring wheat (HRSW, Triticum aestivum L.) in recent years has increased interest for using controlled-release N fertilizers to increase protein concentration while maintaining optimal grain yields. Field experiments were conducted during 6 site-years in Minnesota from 2007 to 2009 to examine eff ects of a polymer-coated urea (PCU, Environmentally Smart Nitrogen [ESN], Agrium Inc., Calgary, AB, Canada) and non-coated urea on grain yields and protein concentrations of two HRSW cultivars, Alsen and Knudson, that vary in grain yield and protein concentration potentials. Polymer-coated urea and urea were applied in spring at six rates that supplied 0 to 110 kg N ha -1 in 2007 and 0 to 168 kg N ha -1 in 2008 and 2009. Because of genetic diff erences, Knudson produced greater grain yield than Alsen in environments (site-years), which were cooler and drier early in the growing season and the yield diff erences between the two cultivars increased with increasing N rates. In the same environment, PCU decreased grain yield compared with urea, which could be related to a reduced N release early in the growing season. Compared with urea, higher N (at Zadoks scale 85) and protein concentrations (at Zadoks scale 92) with PCU were observed due to increased N availability later during the growing season. To increase wheat protein concentrations from using PCU, future studies should evaluate diff erent mixtures of PCU and urea.