Wheat plots at Tribune, Kansas
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Large Scale Dryland Cropping Systems Alan Schlegel, Curtis Thompson, and Troy Dumler
A large-scale rain-fed cropping systems research and demonstration project evaluated four summer crops (corn, grain sorghum, sunflower, and soybean) along with winter wheat in crop rotations varying in length from 2- to 4-years. The objective of the study is to identify cropping systems that enhance and stabilize production in rain-fed cropping systems to optimize economic crop production. Lack of precipitation during the winter and spring depressed wheat yields in 2006. Wheat yields were less following sunflower than sorghum in 3-yr rotations. This trend has been seen in most years, with an average of 9 bu/a lower wheat yields following sunflower than sorghum. In 2006, grain sorghum yields were 41 bu/a greater following wheat than following corn. In 2006, corn yields were reduced by below normal precipitation during pollination. Averaged across the past 12 yr, sorghum has yielded 18 bu/a more than corn when both planted no-till into wheat stubble.
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Land Application of Animal Wastes on Irrigated Corn
Alan Schlegel, Loyd Stone, H. Dewayne Bond, and Mahbub Alam
Animal wastes are routinely applied to cropland to recycle nutrients, build soil quality, and increase crop productivity. This study evaluates established best management practices for land application of animal wastes on irrigated corn. Swine waste (effluent water from a lagoon) and cattle waste (solid manure from a beef feedlot) have been applied annually since 1999 at rates to meet estimated corn P requirements, corn N requirements, or a rate double the N requirement. Other treatments were N fertilizer (60, 120, and 180 lb N/a) and an untreated control. Corn yields were increased by application of animal wastes and N fertilizer. Over-application of cattle manure has not had a negative effect on corn yield. For swine effluent, over-application has not reduced corn yields except in 2004, when the effluent had much greater salt concentration than in previous years, which caused reduced germination and poor early growth.
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Long-Term Nitrogen and Phsphorus Ferilization on Yield of Irrigated Corn Alan Schlegel
Long-term research shows that phosphorus (P) and nitrogen (N) fertilizer must be applied to optimize production of irrigated corn in western Kansas. In 2006, N and P applied alone increased yields about 70 and 30 bu/a, respectively; however, N and P applied together increased yields up to 160 bu/a. Averaged across the past 10 years, corn yields were increased up to 125 bu/a by N and P fertilization. Application of 120 lb N/a (with P) was sufficient to produce maximum yields in 2006, which was slightly more than the 10-year average. Phosphorus increased corn yields in 2006 an average of more than 100 bu/a when applied with at least 120 lb N/a. Application of 80 instead of 40 lb P2O5/a increased yields 20 bu/a when applied with at least 120 lb N/a.
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Four-Year Crop Rotations w/ Wheat and Grain Sorghum
Alan Schlegel, Troy Dumler, and Curtis Thompson
Research on four-year crop rotations with wheat and grain sorghum was initiated at the K-State Southwest Research-Extension Center near Tribune in 1996. The rotations were wheat-wheat-sorghum-fallow (WWSF) and wheat-sorghum-sorghum-fallow (WSSF), along with continuous wheat (WW). Soil water at wheat planting averages about 9 inches following sorghum, which is about 3 inches more than the second wheat crop in a WWSF rotation. Soil water at sorghum planting is approximately 1.5 inches less for the second sorghum crop compared to sorghum following wheat. Fallow efficiency prior to wheat was greater for the shorter fallow period following wheat than for the longer fallow following sorghum. Prior to sorghum, average fallow efficiency was 38-40% and not affected by the previous crop. Grain yield of continuous wheat averages about 75% of the yield of wheat grown in a four-year rotation following sorghum. Except for one year, there has been no difference in yield of continuous wheat and recrop wheat grown in a WSF rotation. Yields are similar for wheat following one or two sorghum crops. Similarly, average sorghum yields were the same when following one or two wheat crops. Yield of the second sorghum crop in a WSSF rotation averages about 70% of the yield of the first sorghum crop.
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No-Till Limited Irrigated Cropping SystemsAlan Schlegel, Loyd Stone, and Troy Dumler
Research was initiated under sprinkler irrigation to evaluate limited irrigation in a no-till crop rotation. With limited irrigation (10 inches annually), continuous corn was more profitable in 2006 than were multi-crop rotations including wheat, sorghum, and soybean. Averaged across the past 4-yr, continuous corn has been the most profitable system primarily because of spring freeze and hail damage to the wheat in the multi-crop rotations. In multi-crop rotations, relatively poor results with one crop (in this case wheat) can reduce profitability compared to a monoculture especially when the monoculture crop does well. However, the multi-crop rotation may reduce economic risk when the monoculture crop does not perform so well. All of the multi-crop rotations had net returns only $20/acre less than continuous corn so only relatively small changes in prices or yields would be needed for any of the rotations to be more profitable than continuous corn indicating the potential for alternate crop rotations under limited irrigation
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Effect of Tillage Intensity in a Wheat-Sorghum-Fallow RotationAlan Schlegel, Loyd Stone, Troy Dumler, and Curtis Thompson
Grain yields of wheat and grain sorghum increased with decreased tillage intensity in a wheat-sorghum-fallow (WSF) rotation. Averaged across the past 16 years, no-till wheat yields were 4 bu/a greater than with reduced tillage and 8 bu/acre greater than with conventional tillage. In 2006, wheat yields were very low but no-till produced 16 bu/a while reduced or conventional tillage resulted in almost complete failure. Grain sorghum yields were also low in 2006 and similar to wheat, no-till sorghum yielded 29 bu/a while conventional or reduced tillage sorghum yielded less than 5 bu/a. Averaged across the past 16 years, no-till sorghum yields were 14 bu/a greater than with reduced tillage and 33 bu/acre greater than with conventional tillage. Averaged across the past 6 years, sorghum yields were 25 bu/a greater with long-term no-till compared to short-term no-till.
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Skip Row Corn for Improved Drought ToleranceAlan Schlegel
Research on skip row planting of dryland corn was initiated at the K-State Southwest Research-Extension Center near Tribune in 2004. The objective was to determine whether some pattern of skipping rows would improve drought tolerance of dryland corn. The planting arrangements were to plant one row and skip one (P1S1); plant two rows and skip one (P2S1); plant two rows and skip two (P2S2); and plant every row (P-All). Target plant populations were 10,000, 15,000, and 20,000 plants per acre. Corn was no-till planted into standing wheat stubble in early May of each year from 2004 to 2006. Corn yields were above average in 2004 and 2005, with yields above 90 bu/a in both years. In these high-yielding years, corn planted every row at a plant population of 15,000 acre-1 produced the highest yields; however, the P1S1 arrangement produced similar yields. The other two planting arrangements (P2S1 and P2S2) tended to reduce yield. In 2006, yields were less than 50 bu/a and corn planted every row at 15,000 plantsa again produced the best yields, although similar yields were obtained with all other planting arrangements. Plant population had more impact on yield that skip row planting. In 2004, with yields in excess of 100 bu/a, yields increased with plant population, while in 2006, with much lower yield potential, yields were generally better with lower plant populations. Overall, yields similar to those of every-row planting could be obtained with skip-row planting in low- and high-yielding years; however, skip-row planting did not result in higher yields than every-row planting in any year.
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Long-Term Nitrogen and Phosphorus Fertilization on Yield of Irrigated Grain SorghumAlan Schlegel
Long-term research shows that phosphorus (P) and nitrogen (N) fertilizer must be applied to optimize production of irrigated grain sorghum in western Kansas. In 2006, N and P applied alone increased yields about 50 and 18 bu/a, respectively; while N and P applied together increased yields more than 65 bu/a. Averaged across the past 10 years, sorghum yields were increased more than 50 bu/a by N and P fertilization. Application of 40 lb N/a (with P) was sufficient to produce >90% of maximum yield in 2006 and for the 10-year average. Application of K has had no effect on sorghum yield throughout the study period.