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Fluid Journal : Fluid Journal 2008-2009
way to apply early-season N. Early-season P. Our data showed no grain yield responses on soils testing high to very high in plant-available P and that one grain yield response of 12 bu/A was obtained on a medium testing soil. Research on poorly drained, cooler soils in continuous no-till has shown that corn yield can be improved most consistently by placing a small amount (10gal/A of starter fertilizer (10-15-0) over the seed zone. More consistent corn yield increases were obtained in Figure 1. Percent N in whole corn plant (12-15 in. height) related to starter-band and broadcast N applications on a Slagle silt loam soil (Alley et al., 2007). Soil Series Optimum starter- band N Rate* Optimum Sidedress N Rate* Yield** Lbs N/acre Lbs N/acre Bu/acre Pamunkey sil 66 0 89 Slagle sil 70 93 168 Pamunkey fsl 70 80 154 Slagle Sl 49 125 128 Turbeville 27 107 111 Cullen l 44 58 126 Eubanks sil 70 0 122 Ross l 40 93 105 Pamunkey sil 70 93 148 *Optimum starter band and sidedress N rates were the combination of starter-band and sidedress rates that resulted in the highest yield for the site. Starter-band N rates were 10, 30, 50 and 70 lbs/A. These were applied in combination with sidedress N rates of 0, 60, 120, and 180 lbs /A. **Multiple regression analyses were used to determine the combination of starter- band and sidedress N that produced the highest yield at each site. Starter-band N (lbs N/acre) 01 02 03 04 05 06 07 08 0 Percent N in Tissue 2.0 2.2 2.4 2.6 2.8 3.0 3.2 3.4 3.6 Broadcast 60 lbs N/acre plus Starter-band 10 lbs N/acre Table 1. Starter band and sidedress N rates for achieving highest yields in 9 no-till corn field experiments in the Virginia Coastal Plain. conjunction with the use of row cleaners and injecting additional N below the surface residues. Wheat Banded P. For no-till winter wheat, supplying fertilizer nutrients in proximity to the seed at planting and below the surface residue may increase fall tiller and root system development and lead to higher yields. Other studies have shown seed-banded P on acid soils with high soil test P levels increased total season wheat forage yield. In our work, placing P in-furrow at planting increased tillering, early growth, and P uptake in another study. Wheat grain yield responses have been shown to be related to increased NandPuptakewhereNandP fertilizers were placed below previous crop residues for wheat planted no-till into corn or soybean residues. In a Virginia study with N and P application methods for winter wheat, early-season growth responses were found for banded-at-seeding applications of N and P, but no grain yield responses were observed. N:P ratios for corn Data from our Virginia trials clearly indicate that relatively high rates of N are needed in banded starter fertilizers, and that P applications can be determined by soil testing. Our recommendations for corn aretoapplyNat50lbs/Aina2x 2 starter band in conjunction with needed P2O5 in the starter band when P needs are low to moderate (i.e., 0 to 50 lbs P2O5/A). This rate of P covers the vast majority of soils used for corn production in the mid-Atlantic region. In most cases, either a 1:1 N:P ratio starter fertilizer such as 15-15-0 material can be used, or on high-available P soils, starter fertilizers with ratios of 2:1 N:P, such as a 20-10-0, can be used to maximize corn response to N, assure adequate early-season P, and optimize both N and P efficiency. For very high levels of soil-test-available P, starter applications (2 x 2) of N only, using either UAN or urea, provide the benefits of increased early-season N availability and early- season vigor. In no-till systems, data from regions with cooler dry season temperatures indicate that starters may be needed in small amounts to enhance early-season growth and maintain consistently high yields, even on high P-testing soils. Dr. Alley is the W.G. Wysor Professor of Agriculture, and Dr. Thomason is extension grains specialist in the Department of Crop and Soil Environmental Sciences at Virginia Tech, Blacksburg, VA.
Fluid Journal 2005-2007