SOIL CRUSTING AND WATER INFILTRATION AFFECTED BY LONG-TERM TILLAGE AND RESIDUE MANAGEMENT

Soils with low organic carbon (OC) are prone to crusting. The objective of this study was to investigate effects of tillage and N-fertility on crusting and water infiltration. Experiments were conducted on two long-term winter wheat (Triticum aestivum L.) -fallow studies. Primary tillage treatments on a tillage study started in 1940 were moldhoard plow, disk, and sweep, with fertilizer rates of 45 and 180 kg N ha(-1). Primary tillage on a residue management study started in 1931 was spring moldboard plowing. Residue management consisted of wheat straw burned in fall with no added N (FB), 22.4 tons ha(-1) of strawy manure every other year (SM), and PO kg N ha(-1) every other year (N90). Water infiltration did not differ among tillage treatments but was 57% greater on 180 kg N ha(-1) than on 45 kg N ha(-1). Porosity of the surface crust on 180 kg N ha(-1) was 12% greater than on 45 kg N ha(-1) and 29% greater on SM than on FB. There was a 14% increase in porosity of the surface crust during winter on SM and N90 and a decrease in porosity on FB. Organic C was 62% greater on SM than on PB. Porosity was significantly correlated (r = 0.75) with OC on the tillage and residue studies. Management practices that conserve or increase OC are important to develop porous soils with high infiltrability.