Crop yield and soil condition under ridge and chisel-plow tillage in the northern Corn Belt, USA

Ridge tillage is a special conservation tillage method, but the long-term e ffect of this tillage system on crop yield and soil quality in a corn (Zea mays L,) and soybean [Glycine mm (L.) Merr.] rotation is largely unknown in the northern Corn Belt of the USA. Our objectives were to compare crop per formance and soil condition at three nitrogen-fertilizer levels under ridge tillage (RT) and conventional tillage (CT). The experiment was started in 1990 at Brookings, SD, on a Barnes clay loam (US soil taxonomy: fine-loamy, mixed Udic Haploboroll; FAO classification: Chernozem). CT included moldbo ard or chisel plowing, seedbed preparation with tandem disk and field culti vator, and raw cultivation. Raised beds under RT were maintained using only row cultivation. Corn grain yield was significantly (p less than or equal to 0.10) greater on CT than on RT. Average (11 years and three fertilizer-N rates) corn yield was 6267 kg ha(-1) with RT and 6500 kg ha(-1) with CT. S oybean grain yield was not significantly (p less than or equal to 0.10) dif ferent between RT and CT. Average (11 years and three fertilizer-N rates) s oybean yield was 1997 kg ha(-1) with RT and 2058 kg ha(-1) with CT. In 9 of 11 years there was a significant soybean-yield response to N-starter ferti lizer. There was no significant accumulation of NO3-N in the top 3 m of soi l at the end of 9 years in either tillage treatment (111 kg NO3-N ha(-1) un der RT and 121 kg NO3-N ha(-1) under CT). Soil pH in the top 15 cm was unaf fected by tillage (average pH was 6.62). In 1999, soil organic C in the top 0.2 m was significantly greater under CT (56 Mg ha(-1)) than under RT (52 Mg ha(-1)). Bulk density in the top 0.2 m was significantly greater under R T (1.52 g cm(-3)) than under CT (1.44 gr cm(-3)). Tillage did not have a gr eat effect on grain yield or soil properties. RT can protect soil from eros ion because crop residues remain relatively undisturbed on the soil surface in contrast to chisel plow. In this respect, we expect RT to be more susta inable over the long term than chisel plow tillage. (C) 2001 Elsevier Scien ce B.V. All rights reserved.