Conservation Tillage Systems for Corn Production on a Loessial Silt Loam and Alluvial Clay in Louisiana

Corn acreage has increased in recent years in Louisiana. Much of this is on mixed to heavy Mississippi River alluvial soils and to a lesser extent on loessial silt loams of the Macon Ridge. Each of these soil groups are unique in their phys­ ical and chemical characteristics and different management strategies may be required to produce optimal yield. Research has indicated that corn performs best when plant­ ed early. Soil water within the rhizosphere may not be as plant available on clay as silt loam alluvial soils partly due to less efficient root development and physiology, making clays more drought prone. Thus, early planting dates on clay soils may be more critical than on the more coarse-textured soils. Ad­ ditionally, planting in many years may be delayed because of poor seedbed conditions on clay soils, particularly if primary tillage operations are performed in early spring. Spring tillage typically produces cloddy seedbeds requiring rainfall or irrigation to produce optimal planting conditions. According to Boquet and Coco (1993), one of the principal advantages of no-till systems is more timely planting, espe­ cially on the poorly drained, clayey soils. Herbek et al. (1986) found a trend for corn yield to increase as planting date increased from late April to mid-May for the no-till system on a poorly drained soil, while yield for the conventionallytilled plots decreased with delayed planting date. In a Louisiana study, Hutchinson et al. (1994) found on the Macon Ridge only small differences in corn yield among conventional-till, reduced-till, and no-till treatments. Although limited tillage research on corn has been conduct­ ed in Louisiana, no-till or minimum-tillage production sys­ tems for cotton have shown promise when compared to the more traditional tillage practices on alluvial clays of the Mis­ sissippi River (Boquet and Coco, 1993; Crawford, 1992; Rey­ nolds, 1990) and on the Macon Ridge (Hutchinson and Shelton, 1990). The inclusion of winter cover crops in com­ bination with conservation tillage was found to be an impor­ tant component of the systems. The use of minimum-tillage systems may reduce soil ero­ sion, especially on the sloping silt loams of the Macon Ridge