Immediate and residual effects of zone-tillage in rotation with no-tillage on soil physical properties and corn performance

Abstract

A potential constraint to the no-tillage production of corn ( Zea mays L.) is soil densification from lack of tillage and wheel traffic. This study examines the extent and duration of the effects of periodic (rotational) zone tillage over 3 years on selected soil physical properties and corn performance. Four tillage treatments — chisel plow (CP), no tillage (NT), and two zone-tillage (ZT) treatments were evaluated on a Riddles loam (Typic Hapludalf, fine-loamy, mixed, mesic) soil. The two ZT treatments consisted of subsoiling in the row with a Bush Hog Rotill (RT) (Bush Hog, Selma, AL) or a Paratill (PR76) (Tye, Lockney, TX) subsoiler, or full-width subsoiling with a Paraplow (PR51) set at 51 cm shank spacing. Corn followed either corn or a small grain so that residues from the previous crop were about 7–9 Mg ha −1 after harvest. Crop residues on the soil surface were less than 25% after planting in the CP treatment and in the row of the RT treatment. Corn yields were reduced by 0.7–0.9 Mg ha −1 in 1985 in the NT compared with the ZT and CP treatments. Corn yields were similar for all treatment-year combinations in 1986 and 1987. Final populations were reduced in the year of tillage for the PR treatments in 1985 and 1987, but this did not significantly affect yields. The immediate effects of subsoiling on soil physical properties were significant but not different between the two ZT treatments. Soil strength as measured by cone index approached 3.0 MPa in the NT treatment and was reduced to less than 0.5 MPa by ZT over the 30 cm sampling depth, and by CP only in the 0–10 cm soil depth. Bulk density, total and air-filled porosity, and saturated hydraulic conductivity were all improved by CP and ZT. However, CP had little effect below 10–15 cm, whereas ZT improved conditions to a soil depth of 30 cm. Zone-tillage showed some residual effects on soil properties over the 2 years following tillage. Cone index increased with time but remained below 1.0 MPa over the 30 cm sampling depth. Air-filled porosity over the range of −2 to −100 kPa matric potential declined to NT levels at all soil depths within 2 years. Bulk density and total porosity declined to NT levels in the 0–7.5 and 7.5–15 cm depths but remained significantly improved over NT in the 22.5–30 cm soil depth. Macroporosity created by ZT consolidated in the years following tillage to the extent that microporosity in the ZT treatments was significantly greater than NT. While improved soil physical conditions at depth improved corn yields only in 1985 on this soil, ZT may have potential as a partial width rotational tillage system with NT as it improves soil conditions while maintaining many conservation benefits of NT.