Yield and Nitrogen Uptake of Spring Wheat Planted in a Ridge-Till System

Conservation tillage and inclusion of a cover crop that provides surface residue cover are two management options for reducing soil erosion losses commonly found in a corn (Zea mays L.)-soybean [Glycine max (L.) Merr] rotation. Information is lacking, however, on the performance of a small grain planted in a ridge-tillage system in the Northern Corn Belt. A 3-yr (1992–1994) study was conducted to determine the effect of row position (ridge, shoulder, furrow, and wheel track furrows) on yield and N uptake of hard red spring wheat (Triticum aestivum L.) planted in a ridge-tillage system on poorly drained Webster clay loam (fine-loamy, mixed, mesic Typic Haplaquoll) soil at two locations in southern Minnesota. Spring wheat was planted after soybean in 15 ft wide strips. Wheat performance was affected by the position of the row across the ridged seedbed. Averaged across the 3 yr, grain yield of the wheat rows planted on ridge top and shoulder positions was 31% greater than those rows planted in the furrows at both locations. Grain yield of wheat in the wheel track furrows was reduced by 38% at Freeborn and by 33% at Waseca compared with those planted on ridge tops and shoulders when averaged across years. Moreover, grain yield in the wheel track furrows was reduced by 18% at Freeborn and by 12% at Waseca compared with non-wheel track furrows across years. Similar to grain yield, straw yield and total N uptake were greater in the ridge top and shoulder positions than in either non-wheel track or wheel track furrow positions. Lesser grain yield in the furrows and wheel track furrows correlated well with reduced head numbers in these row positions compared with ridge top and shoulder positions. The results from this study indicate that wheat can be successfully planted in a ridge-tillage system. Yield losses, however, occur in the furrows and controlled wheel track furrows, especially in wet years in this ridge-till system. Research QuestionA corn-soybean rotation predominates in the Corn Belt of the Midwest since both corn and soybean yield more in a rotation than in monoculture. Soil erosion losses, however, are greater with this rotation than with continuous corn because soybean residues decompose quickly after harvest and soil is exposed to wind and water erosion. Ridge tillage and inclusion of a small grain that provides surface residue cover are two management options to reduce soil erosion losses commonly found in a corn-soybean rotation. The objective of this study was to determine the effect of row position on yield and N uptake of hard red spring wheat planted in a strip-intercropped, ridge-till system on poorly drained soils in southern Minnesota. Literature SummaryPast research conducted with winter wheat in Kansas reported that wheat yields in a ridge-tillage system were comparable to or greater than those planted in conventional or reduced tillage systems. In wet years, poor yields in the wheat rows planted in the furrows contributed to less yield whereas in a dry year, wheat planted in the furrows contributed to greater yield. Information is lacking, however, on the performance of a spring wheat planted in a ridge-tillage system in the Northern Corn Belt where spring soil temperatures are cold and small grain establishment may be more difficult. Study DescriptionThe study was conducted on a poorly drained Webster clay loam soil at two locations in southern Minnesota from 1992 to 1994. Hard red spring wheat, variety ‘Grandin’, was planted at a rate of 94 lb/acre in 8-in. rows in strips that were 15-ft wide by 120-ft long allowing 22 rows per strip. Corn was located on the south side and soybean on the north side of the wheat strip in east-west rows at one location. In north-south rows, soybean was located on the east side and corn on the west side of the wheat strips at the second site. Wheat was planted directly into the soybean stubble without secondary tillage using a 15-ft John Deere 515® minimum till drill following a broadcast application of 50 lb N/acre as ammonium nitrate. Ridge height ranged from 4.5 to 5.5 in. Applied QuestionsCan a small grain crop such as wheat be successfully planted in a ridge-tillage system? Yes. We varied the down pressure by lowering the arms and adjusting the spring tension on the units in the furrow and raising the ones on the ridges in order to achieve uniform planting depth across the ridged seedbed. This helped to achieve a uniform emergence and stand of wheat across the rows without destroying the remaining soybean residue in our study. Grain yields of the whole strip averaged 40 bu/acre at one site and 45 bu/acre at the second site during the 3 yr (Table 1). Does row position have an effect on wheat yield and N uptake? Yes. Grain yield (3-yr average) of the wheat rows planted on the ridge tops and shoulders was 10 bu/acre greater at Freeborn and 11 bu/acre greater at Waseca than those rows planted in the furrows (Table 1). Straw yield for the ridge tops and shoulders was 22 and 34% greater at Freeborn and Waseca, respectively, compared with the rows in the furrows across years. Total N uptake for the rows planted on the ridge tops and shoulders was 24 to 32% greater than the rows in the furrows at both locations when averaged across years. What effect did controlled wheel traffic have on wheat yield and N uptake? Grain yield of the wheat rows planted in the wheel tracks was 38% less at Freeborn and 33% less at Waseca than those rows planted on ridge tops and shoulders across the years (Table 1). Straw yield of the rows planted in the wheel track furrows was reduced by 32 and 38% at Freeborn and Waseca, respectively, compared with those of the rows on the ridge tops and shoulders during the 3 yr. Averaged across years, total N uptake of wheat planted in the wheel track furrows was only about 63% of those planted on the ridge tops and shoulders. The effect of wheel tracks was much more severe in a wet year (1993) at Waseca, where grain yield in the wheel track bows was 21 bu/acre less than those rows planted on ridge tops and shoulders and 8 bu/acre less than those in the non-wheel track furrows. The higher yield on ridge tops nearly offsets the lower yields of wheel track rows and non-wheel track furrows, thereby making the overall strip yields more competitive in this ridge-till system. Table 1Three-year (1992–1994) average grain yield, straw yield, and total N uptake of spring wheat as influenced by row position in a ridge-tillage system at Freeborn and Waseca. FreebornWasecaNo. ofGrainStrawTotal NGrainStrawTotal NRow positionrowsyieldyielduptake†yieldyielduptake†bu/acreton/acrelb/acrebu/acreton/acrelb/acreRidge647.11.51106.151.41.4698.6Shoulder1040.41.3793.346.71.3691.7Furrow Non-wheel tack333.31.1880.137.51.0571.8 Wheel track227.30.9864.032.90.8760.0Whole-strip‡2140.01.3492.345.41.3087.8†Two-year (1992–1993) average. ‡Whole-strip average calculated by taking weighted means (each value times number of rows).