|Frederick, James - CLEMSON UNIVERSITY|
Submitted to: Southern Conservation Tillage for Sustainable Agriculture Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: March 17, 2000
Publication Date: N/A
Technical Abstract: Because the soils of the Coastal Plain are easily compacted, most farmers use in-row subsoiling to loosen the soil directly under the row. Often, farmers return to the same row area with the subsequent crop to re-use old subsoil slits or to reduce the soil area compacted by tractors and equipment. We measured the horizontal and vertical distribution of soil P and K after six years of growing crops in 30-in rows with conservation tillage and controlled traffic. As expected, highest concentrations of P occurred in the surface 2-in of the profile. Higher concentrations of P occurred in the row middles than directly in the row, both with and without subsoiling. Higher yields with subsoiling caused greater P removal in the seed, resulting in those plots having lower P levels than those that were not subsoiled. The horizontal distribution of K was opposite than was found for P. In the surface soil there was higher concentrations of K in the soil in the row than in the soil in the row middles. Averaged over both row locations, K levels is the surface three inches of the B horizon were lower in plots that were subsoiled than in the no-subsoiled plots. This suggests greater root concentration and more nutrient uptake from that horizon in the subsoiled plots. When soil sampling for fertilizer needs in long-term conservation tillage fields, care must be taken to collect samples from both in the rows and in the row middles.