Submitted to: Soil & Tillage Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/10/2002
Publication Date: 7/1/2002
Citation: BAUER, P.J., FREDERICK, J.R., BUSSCHER, W.J. TILLAGE EFFECT ON NUTRIENT STRATIFICATION IN NARROW- AND WIDE-ROW CROPPING SYSTEMS. SOIL & TILLAGE RESEARCH. 2002. V.66. P. 175-182.
Interpretive Summary: A representative soil sample is the best way farmers can tell how much fertilizer to apply to their fields. Tillage practices influence the distribution of the nutrients in the soil. Our objective was to measure how nutrient distribution in the soil varies between different tillage systems and between narrow- and wide-row cropping systems. We found that in the wide-row system that most farmers are using now, distribution of nutrients differs quite a bit between conventional (mixing the surface soil with a disk plough) and conservation tillage (direct seeding of crops into the old crop residue). This means that in wide-row spacing, farmers need to consider altering their sample collection techniques soon after converting to conservation tillage. In the narrow-row system, however, the difference between conservation tillage and conventional tillage was small, even after six years, suggesting existing methods of sampling fields are adequate in that system. These findings are important to extension personnel and to private consultants providing farmers advice on fertilizer management. This information is also important to scientists developing improved crop production methods, like growing corn and soybeans in narrow rows.
Technical Abstract: Conservation tillage production systems on many soils of the southeastern USA coastal plain commonly include subsoiling to disrupt compacted zones. The objective of this study was to determine how surface tillage and subsoiling affect nutrient distribution in the soil profile with crops grown in traditional wide-row and in narrow-row arrangement. Soil samples were collected in 1996 from plots that had been growing wheat (Tritiucm aestivum L.) doublecropped with soybean (Glycine max L. Merr.) for three years and then again in 1999 after three years of continuous corn (Zea mays L.). Narrow row spacing was 19 cm for soybean and 38 cm for corn. Wide row spacing was 76 cm for both soybean and corn. Treatments were surface tillage [disk tillage (DT) and no tillage (NT)], with different frequencies of subsoiling. The soil type was Goldsboro loamy sand (fine-loamy, siliceous, thermic, Aquic Kandiudult). Soil samples from four depths were analyzed for P, K, Ca, and Mg. Few differences between DT and NT occurred for nutrient concentrations in the narrow row system at any depth. In the wide row system, P, Mg, and Ca concentrations at the soil surface tended to be higher in NT than in DT, especially in row middles. Relatively large differences in all four nutrient concentrations occurred between row positions at the soil surface in the wide row culture, especially with NT after corn. Subsoiling had little effect on nutrient concentrations at any depth in either system. When fields are converted to conservation tillage production practices, it appears that changing soil sampling procedures for determination of fertility status is more critical in fields where wide row culture is used.