Soybean yield as affected by crop rotations, deep tillage and irrigation layout on a hardsetting Alfisol (vol 44, pg 151, 1997)

The hardsetting surface of many Alfisols in Australia is a limiting factor in crop production. Better soil management systems are required to improve productivity. This study reports the effects of several untested management systems, involving the combined effects of tillage (deep ripping, deep mou ldboard ploughing and disc ploughing), irrigation layout (permanent beds, b order ditch) and crop rotation treatments (single cropping, double cropping and pasture), on soil structure and the production of irrigated soybeans [ Glycine max (L) Merr.] on a hardsetting Alfisol. It was conducted under a s ystem of controlled traffic near Trangie, NSW, Australia. The double croppi ng and pasture treatments increased total water entry, soil organic carbon and soybean leaf water potential. Consequently, soybean yield was increased by as much as 58%. The retention of cereal and pasture stubble increased t otal water entry by slowing the rate of irrigation water advance, reducing the potential for slaking and increasing the number of continuous vertical macropores. The increases in soil water were associated with a reduction in soil strength; a key limiting factor in crop growth on hardsetting Alfisol s. Deep tillage or the use of permanent beds did not affect soybean yields under the conditions reported in this paper, although the combination of di sc ploughing and furrow irrigation was successful. (C) 1999 Elsevier Scienc e B.V. All rights reserved.