Long-term tillage and crop rotation effects on soil quality, organic carbon, and total nitrogen

Abstract

Long-term studies allow for quantification of the effects of crop production practices, such as tillage and crop rotation, on soil quality and soil C and N stores. In two experiments at Ridgetown, ON, we evaluated the long-term (11 and 15 yr) effect of tillage system and crop rotation on soil quality via the Cornell Soil Health Assessment (CSHA) at 0Á15 cm and soil organic C (SOC) and total N at 5-, 10-, and 20-cm increments to 120 cm depth. The CSHA soil quality score and SOC and total N were higher with no-till (NT) than fall moldboard plough with spring cultivation (conventional tillage, CT) and rotations with winter wheat [soybeanÁwinter wheat (S-W) and soybeanÁwinter wheatÁcorn (S-W-C)] compared with rotations without winter wheat. In both long-term trials, NT had ca. 21 Mg ha (1 more or 14% higher SOC than CT in the 0-to 100-cm soil profile, a trend which contrasts previous research in eastern Canada. Thus, the two long-term trial results at Ridgetown suggest that to improve soil quality and storage of C and N, growers on clay loam soil in southwestern Ontario should consider adopting NT production practices and including winter wheat in the rotation.

Long-term impact of tillage and crop rotation on soil health at four temperate agroecosystems

“…Campbell et al (1993) found aggregate stability was influenced by long-term (30 years) management; long-term CT probably disturbed soil aggregates, facilitating a more rapid breakdown of crop residues than NT, thereby reducing aggregate stability. Likewise, previous long-term (9-12 years) research found higher aggregate stability in NT or minimal till plots than chisel or plow treatments in monoC or rotational C cropping in WI, USA (Karlen et al, 1994) at Elora, ON (Raimbault and Vyn, 1991) and Ridgetown, ON (Van Eerd et al, 2014). The higher aggregate stability in NT vs. CT may be in part a reflection of earthworm activity as influenced by tillage.…”

“…The higher aggregate stability in NT vs. CT may be in part a reflection of earthworm activity as influenced by tillage. For example, earthworm midden counts were higher in NT compared to CT after long-term management at Ridgetown (Van Eerd et al, 2014) and elsewhere (Karlen et al, 1994), presumably because Table 3 Effect of crop rotation a on overall Cornell Soil Health Assessment (CSHA) and Ontario Soil Health Assessment (OSHA) score b in 0-15 cm depth from four long-term experiments.…”

“…Crop rotation was the split-plot factor; which included monoculture corn (Zea mays L.) (monoC), monoculture soybean (monoS), soybean-winter wheat (S-W), corn-soybean-winter wheat (C-S-W), and soybean-corn (S-C) rotations. Fertilizer applications were previously reported (Van Eerd et al, 2014); briefly, 100 kg ha À1 of starter (6-24-24) applied at corn planting, with a sidedress injection of 120 kg N ha À1 of urea ammonium nitrate (28-0-0) annually. For winter wheat 100 kg N ha À1 as calcium ammonium nitrate (27-0-0) was broadcast on the soil surface and no N fertilizer was applied for soybean production.…”

“…The typical depth of soil disturbance for NT, moldboard plow and cultivation was 5 cm, 15-20 cm and 10-15 cm, respectively. At Ridgetown (42 26 0 N 81 53 0 W) on a clay loam soil with 27% sand, 37% silt, and 36% clay (Orthic Humic Gleysol) in 1995, a longterm tillage system and crop rotation trial was established in a split-plot design with four replicates, as described by Van Eerd et al (2014). The main plot factor was tillage: NT (no soil disturbance except during planting) and CT (moldboard plow in the autumn followed by spring cultivation for seedbed preparation, as per typical production practices).…”

“…However, the simple un-weighted average approach of the CSHA may result in a biased soil health score due to extreme values from individual soil attributes. Improvements in calculating or computing the overall soil health score may be required for a more meaningful representation of overall soil health (Van Eerd et al, 2014). Furthermore, research is needed to assess the applicability of the CSHA for Ontario soils and elsewhere.…”