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Fluid Journal : Fluid Journal 2002-2004
Strip-till or zone-till is suggested as an alternative to no-till in these northern climates where soils are cold at the time of planting and are slow to warm. This fall tillage method disturbs the soil to a 7- to 8-inch depth and creates a 4- to 6- inch wide by 1- to 2-inch high mound of soil that is free of residue. Corn can be planted early and directly into the strip area that is warmer and drier. One-pass, secondary tillage systems consist of no fall primary tillage and either field cultivation or a disking operation in the spring. This system is now quite popular for corn following soybeans in the Corn Belt. Use of conservation-till practices limits the opportunity for incorporation of P- containing fertilizers that are broadcast on the soil surface. Therefore, optimum placement of P is essential in reduced-till systems, especially in soils testing low in P. Thus, one purpose of this long- term study is to determine the effect of P placement on corn and soybean yields in three reduced-till systems and one conventional-till system for corn/ soybean rotations. LOW-TESTING SOILS Corn yields in 2001 were lower than expected due primarily to very wet conditions from April 5 to June 15 (16.5 inches of rain) followed by below normal rainfall from June 16 to August 15 (4.9 inches) and very hot temperatures (18 days greater than 90o F). Under these stress conditions, large yield responses to P were obtained on this low-testing soil with all four tillage systems (Table 1). Averaged across similar P manage- ment strategies (no P and starter P) yields were not significantly different among tillage systems. The yield response to starters averaged 35 bu/A across the four tillage systems with no tillage by starter interaction. Corn yields were 8 to 12 bu/A greater for the broadcast P (100 lbs/A of P2O5) com- Table 2. Soybean yield in a corn/soybean rotation on a low P testing soil as affected by tillage and P management strategies for corn in 2001 and the 4-year avg. Tillage P mgt. P2O5 Yield Corn Soybean lbs/A bu/A 2001 1998-01 avg. No-till No-till Check 0 29.1 34.8 Starter 50 51.7 47.7 Field cult. Spr. disk Check 0 31.2 36.0 Starter 50 51.1 48.2 Fall band 50 49.2 48.0 Spr. b'cast 100 53.6 52.5 Strip-till No-till Check 0 36.7 37.9 Starter 50 50.2 49.1 Fall band (f) 50 47.0 47.8 Fall band (r) 50 42.2 43.5 Fall band (f) 100* 49.3 Chisel Chisel Check 0 28.5 32.4 Starter 50 52.0 50.8 Fall b'cast 100 52.4 53.7 (f) = fixed in same position each year prior to planting corn (r) = random and band moved 8 inches laterally each year prior to planting corn * This treatment first applied in fall 1999 for the 2000 corn crop. Table 3. Corn yield in a corn/soybean rotation on high P- testing soil as affected by tillage and P management strategies in 2001 and the 5-year avg. Tillage P mgt. P2O5 Yield lbs/A bu/A 2001 1997-2001 avg. No-till Check 0 134 155 Starter 40 143 156 Field cult. Check 0 135 161 Starter 40 142 165 Fall band 40 146 161 Spring b'cast 80 157 171 Strip-till Check 0 147 161 Starter 40 147 165 Fall band (f) 40 148 160 Fall band (r) 40 149 165 Fall band (f) 80* 152 Chisel Check 0 153 167 Starter 40 153 168 Fall b'cast 80 153 171 (f) = fixed in same position each year (r) = random and band moved 8 inches laterally each year prior to planting corn * This treatment first applied in fall, 1999.
Fluid Journal 1999-2001
Fluid Journal 2005-2007