Continuous corn with moldboard tillage: Residue and fertility effects on soil carbon

• Published in: Journal of soil and water conservation Vol. 57; no. 5; pp. 277 - 284
• Main Authors: REICOSKY, D. C, EVANS, S. D, CAMBARDELLA, C. A, ALLMARAS, R. R, WILTS, A. R, HUGGINS, D. R
• Format: Journal Article
• Language: English
• Published: Ankeny, IA Soil and Water Conservation Society 01.09.2002; Soil & Water Conservation Society
• Subjects: Agronomy. Soil science and plant productions; Applied sciences; Atmospheric pollution; Biological and medical sciences; Carbon content; Carbon dioxide; Chemical, physicochemical, biochemical and biological properties; Computer programming; Corn; Crop yields; Crops; Cultivation (Land); Environmental aspects; Evaluation; Exact sciences and technology; Fertility; Fundamental and applied biological sciences. Psychology; Measurement; Methods; Organic matter; Physics, chemistry, biochemistry and biology of agricultural and forest soils; Pollution; Soil carbon; Soil productivity; Soil science; Soils; Tillage; Organic carbon; Nitrogen fertilization; Monocotyledones; Zea mays; Soil fertility; Carbon dioxide; Experimental study; Carbon sequestration; Cereal crop; Carbon balance; Gramineae; Greenhouse gas; Crop residues; Conventional tillage; Angiospermae; Air pollution; Spermatophyta; SOIL ORGANIC MATTER
• ISSN: 0022-4561; 1941-3300

Greenhouse gas emissions from soil depend on land use, cropping systems, and tillage methods. The impact of 30 years of continuous corn ( Zea mays L.) with moldboard plow tillage was evaluated from four treatments and a control: silage removal versus grain removal, each with low [83 kg N ha −1 (74 lb N ac −1 )] and high [166 kg N ha −1 (148 lb N ac −1 )] fertility, and no added fertilizer with grain removal. Soil organic carbon (SOC) changes over a 30-yr period were measured, as well as tillage-induced CO 2 loss immediately after moldboard plowing, in the spring of 1996. The 24 h cumulative tillage-induced CO 2 loss was not significantly different among treatments (excluding the control). Total C, total N, and C:N ratio in the soil remained virtually unchanged after 30 yr in fertilized treatments. All four treatments produced the same SOC content [21.9 g kg −1 (2.2%)] in the 0 - 20 cm (0 - 8 in) depth. The cumulative total input of 241 Mg ha −1 (107 t ac −1 ) of aboveground stover from the high fertility grain treatment, compared to none from the high fertility silage treatment, yielded no differences in SOC. Fertilizer N rates of 83 and 166 kg ha −1 (74 and 148 lb ac −1 ) produced no difference in SOC or associated C:N ratios. Moldboard plow tillage caused rapid soil degassing that masked fertilizer and stover removal and/or return effects on SOC. This uncontrolled SOC decline agreed with other studies in this region, indicating that the soils were sources of CO 2 regardless of other agronomic practices, as long as moldboard plow tillage was used.