RESIDUE MANAGEMENT PRACTICE EFFECTS ON SOIL PENETRATION RESISTANCE IN A WHEAT-SOYBEAN DOUBLE-CROP PRODUCTION SYSTEM

improving long-term agricultural sustainability requires appropriate soil and residue management practices. Soil cone index (CI), which relates to the resistance to penetration of a cone of specific dimensions, is an important physical property relating to soil and crop productivity, particularly in intensive cropping systems. A study was initiated in 2001 to evaluate the effect of alternative residue management practices on soil penetration resistance in a wheat (Triticium aestivum L.)-soybean (Glycine max [L.] Merr.) double-cropped system in the Mississippi River Delta region of eastern Arkansas. Residue management treatments consisted of tillage (conventional tillage and no-tillage [NT]), residue burning (burn and no burn), and residue level (low and high, achieved by differential N fertilization). Soil Cl, as measured using a hand-pushed penetrometer, was determined at 0.05-m intervals to a depth of 0.4 m in 2003, after one, and in 2006, after four complete cropping cycles. The whole-field Cl increased with depth in both years. Tillage, burning, and residue level generally did not affect Cl in the top 0.20-m in either year. In both years, soil CI was consistently lower under burning than nonburning at all depths below 0.20 m. Compared with after only I year, 4 years of NT soybean resulted in a 35% increase in CI at the 0.05-m depth. Soil CI was reduced at the 0.4-m depth under NT and nonburning but increased somewhat under conventional tillage and nonburning after 4 years. Being aware of the potential effects of alternative residue management on soil properties and root growth in relation to soil penetration resistance will be necessary for sustainable soil management practices. (Soil Science 2008;173:779-791)