Carbon Supply and Storage in Tilled and Nontilled Soils as Influenced by Cover Crops and Nitrogen Fertilization

Abstract

Soil carbon (C) sequestration in tilled and nontilled areas can be influenced by crop management practices due to differences in plant C inputs and their rate of mineralization. We examined the influence of four cover crops {legume [hairy vetch (Vicia villosa Roth)], nonlegume [rye (Secale cereale L.)], biculture of legume and nonlegume (vetch and rye), and no cover crops (or winter weeds)} and three nitrogen (N) fertilization rates (0, 60 to 65, and 120 to 130 kg N ha(-1)) on C inputs from cover crops, cotton (Gossypium hirsutum L.), and sorghum [Sorghum bicolor (L.) Moench)], and soil organic carbon (SOC) at the 0- to 120-cm depth in tilled and nontilled areas. A field experiment was conducted on Dothan sandy loam (fine-loamy, siliceous, thermic Plinthic Paleudults) from 1999 to 2002 in central Georgia. Total C inputs to the soil from cover crops, cotton, and sorghum from 2000 to 2002 ranged from 6.8 to 22.8 Mg ha(-1). The SOC at 0 to 10 cm fluctuated with C input from October 1999 to November 2002 and was greater from cover crops than from weeds in no-tilled plots. In contrast, SOC values at 10 to 30 cm in no-tilled and at 0 to 60 cm in chisel-tilled plots were greater for biculture than for weeds. As a result, C at 0 to 30 cm was sequestered at rates of 267, 33, -133, and -967 kg C ha(-1) yr(-1) for biculture, rye, vetch, and weeds, respectively, in the no-tilled plot. In strip-tilled and chisel-tilled plots, SOC at 0 to 30 cm decreased at rates of 233 to 1233 kg C ha(-1) yr(-1). The SOC at 0 to 30 cm increased more in cover crops with 120 to 130 kg N ha(-1) yr(-1) than in weeds with 0 kg N ha(-1) yr(-1), regardless of tillage. In the subtropical humid region of the southeastern United States, cover crops and N fertilization can increase the amount of C input and storage in tilled and nontilled soils, and hairy vetch and rye biculture was more effective in sequestering C than monocultures or no cover crop.

Carbon sequestration in agricultural soils via cultivation of cover crops – A meta-analysis

“…Elevation as such does not add much information to the model and it might be a dataset specific phenomenon that elevation enhances a model explaining SOC dynamics. In fact, the highest SOC stock depletion was found at the highest plot in the dataset (2298 m) (Astier et al, 2006) and the highest annual SOC stock accumulation has been found at one of the lowest plots (16 m) (Sainju et al, 2006). Those extreme values might have strongly determined the explanatory power of the variable "elevation".…”

Arylsulphatase activity and sulphate content in relation to crop rotation and fertilization of soil

“…Knauf et al (2003) investigated the arylsulphatase activity within the rhizosphere of Sinapis album, Lolium perenne, Triticum aestivum and Brassica napus, which were fertilized using organic and mineral fertilizers. The inclusion of a leguminous crop in the crop rotation increases soil enzymatic activity since leguminous crops may secrete higher amounts of exudates into the rhizosphere than non-leguminous crops (Sainju et al, 2006). Therefore, in the present investigations, arylsulphatase activity was determined in soil with two crop rotations: exhausting the soil from organic matter and crop rotation enriching the soil with humus in a longterm field experiment.…”

Cover crop effect on soil carbon fractions under conservation tillage cotton

“…The mild winter of this region is favorable for growing cover crops which increase C inputs and soil organic matter compared with bare fallow (McVay et al, 1989;Schomberg and Endale, 2004;Sainju et al, 2006). Combined with conservation tillage, cover crops have been shown to improve the productivity of degraded soils in the Southeastern USA (Bruce et al, 1995;Sainju et al, 2002).…”

“…Sainju et al (2005bSainju et al ( , 2006 reported that biculture of hairy vetch and rye increased crop biomass C and SOC compared with monoculture of either species or no cover crop. Cover crop mixtures can enhance soil productivity by building active organic matter pools and increasing N mineralization due to their large biomass production compared with individual species (Mutch and Martin, 1998).…”