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Highlights: [•] Two types of tillage (conventional disk and no tillage) were evaluated for soil nitrate impacts. [•] Two types of winter cover cropping (legume-derived N and inorganic fertilizer N) were evaluated. [•] Type of cover crop had little influence on soil-profile nitrate content. [•] Conventional tillage caused greater profile nitrate change than no tillage. [Copyright &y& Elsevier]

Abstract: Grazing of cover crops in grain cropping systems can increase economic return and diversify agricultural production systems, but the environmental consequences of this intensified management have not been well documented, especially under different tillage systems. We conducted a multiple-year investigation of how cover crop management (grazed and ungrazed) and tillage system [conventional (CT; initial moldboard plowing and thereafter disk tillage) and no tillage (NT)] affected soil physical properties (bulk density, aggregation, infiltration, and penetration resistance) on a Typic Kanhapludult in Georgia. Responses were determined in two cropping systems: summer grain/winter cover crop and winter grain/summer cover crop. Soil bulk density was reduced (P =0.02) with CT compared with NT to a depth of 30cm at the end of 0.5 year, but only to a depth of 12cm at the end of 2, 2.5, and 4.5 years. Grazing of cover crops had little effect on soil bulk density, except eventually with 4.5 years of management. Water-stable macroaggregation was reduced (P ≤0.01) with CT compared with NT to a depth of 12cm at all sampling times during the first 2.5 years of evaluation. Stability of macroaggregates in water was unaffected by grazing of cover crops in both tillage systems. Across 7 sampling events during the first 4 years, there was a tendency (P =0.07) for water infiltration rate to be lower with grazing of cover crops (5.6mmmin−1) than when ungrazed (6.9mmmin−1), irrespective of tillage system. Across 10 sampling events, soil penetration resistance was greater under NT than under CT at a depth of 0–10cm (P =0.001) and the difference was greater in ungrazed than in grazed systems (P =0.06). Biannual CT operations may have alleviated any surface degradation with animal traffic, but the initially high level of soil organic matter following long-term pasture and conversion to cropland with NT may have buffered the soil from any detrimental effects of animal traffic. Overall, the introduction of cattle to consume the high-quality cover crop forage did not cause substantial damage to the soil. [Copyright &y& Elsevier]

Abstract: Semiarid Mediterranean climatic conditions and intensive tillage systems accelerate soil organic matter losses. Therefore, assessing agricultural practices that enhance storage of soil organic matter is needed. Stratification of soil properties with soil depth, expressed as a ratio, could indicate soil quality under different soil management. We measured soil depth stratification ratio (0–5/10–30cm and 0–5/30–50cm) of soil organic C (SOC), total N, active carbon (AC), water soluble carbon (WSC), and soil enzymatic activities [dehydrogenase activity (DHA) and β-glucosidase activity (BGA)] of a Typic Haploxerert in southern Spain. The experimental design consisted of a split–split plot design with three replications and soil properties evaluated at the end of 22 years. Tillage systems included conventional tillage (CT) and no tillage (NT). Dryland, 2-year crop rotations were wheat (Triticum aestivum L.)–fallow (WF), wheat–chickpea (Cicer arietinum L.) (WC), wheat–faba bean (Vicia faba L.) (WFb), wheat–sunflower (Helianthus annuus L.) (WS), and continuous wheat (WW). Nitrogen fertiliser rates were 0, 50 and 150kgNha−1. Stratification ratios of total N, WSC, AC, DHA, and BGA were most responsive to tillage systems; NT greater than CT. Stratification ratios of SOC, total N, WSC, AC and BGA were most responsive to crop rotation; WFb and WW greater than WF, WC, and WS. Stratification ratio of BGA was most responsive to N fertiliser rate; higher rates than no fertiliser. Stratification ratios of C and N fractions and enzymatic activities were responsive to choice of denominator used for ratio calculation. Tillage and crop rotation had more influence than N fertiliser rate in affecting stratification ratio of C and N fractions and enzymatic activities. Stratification ratio was relatively low (<2), perhaps due to the large shrinking and swelling characteristics of Vertisols. Stratification ratio of BGA was greater than of all other soil properties, suggesting that it might be a good indicator of soil quality under different soil management in Mediterranean conditions, particularly with Vertisols. This study indicated the value of stratification ratios to detect improvement in soil organic matter fractions and enzymatic activities (i.e. indicators of soil quality) with adoption of improved conservation management approaches. [Copyright &y& Elsevier]