Carbon accumulation in cotton, sorghum, and underlying soil as influenced by tillage, cover crops, and nitrogen fertilization

Abstract

Soil and crop management practices may influence biomass growth and yields of cotton (Gossypium hirsutum L.) and sorghum (Sorghum bicolor L.) and sequester significant amount of atmospheric CO 2 in plant biomass and underlying soil, thereby helping to mitigate the undesirable effects of global warming. This study examined the effects of three tillage practices [no-till (NT), strip till (ST), and chisel till (CT)], four cover crops [legume (hairy vetch) (Vicia villosa Roth), nonlegume (rye) (Secale cereale L), hairy vetch/rye mixture, and winter weeds or no cover crop], and three N fertilization rates (0, 60-65, and 120-130 kg N ha )1 ) on the amount of C sequestered in cotton lint (lint + seed), sorghum grain, their stalks (stems + leaves) and roots, and underlying soil from 2000 to 2002 in central Georgia, USA. A field experiment was conducted on a Dothan sandy loam (fine-loamy, kaolinitic, thermic, Plinthic Kandiudults). In 2000, C accumulation in cotton lint was greater in NT with rye or vetch/rye mixture but in stalks, it was greater in ST with vetch or vetch/rye mixture than in CT with or without cover crops. Similarly, C accumulation in lint was greater in NT with 60 kg N ha )1 but in stalks, it was greater in ST with 60 and 120 kg N ha )1 than in CT with 0 kg N ha )1 . In 2001, C accumulation in sorghum grains and stalks was greater in vetch and vetch/rye mixture with or without N rate than in rye without N rate. In 2002, C accumulation in cotton lint was greater in CT with or without N rate but in stalks, it was greater in ST with 60 and 120 kg N ha )1 than in NT with or without N rate. Total C accumulation in the above-and belowground biomass in cotton ranged from 1.7 to 5.6 Mg ha )1 and in sorghum ranged from 3.4 to 7.2 Mg ha )1 . Carbon accumulation in cotton and sorghum roots ranged from 1 to 14% of the total C accumulation in above-and belowground biomass. In NT, soil organic C at 0-10 cm depth was greater in vetch with 0 kg N ha )1 or in vetch/rye with 120-130 kg N ha )1 than in weeds with 0 and 60 kg N ha )1 but at 10-30 cm, it was greater in rye with 120-130 kg N ha )1 than in weeds with or without rate. In ST, soil organic C at 0-10 cm was greater in rye with 120-130 kg N ha )1 than in rye, vetch, vetch/rye and weeds with 0 and 60 kg N ha )1 . Soil organic C at 0-10 and 10-30 cm was also greater in NT and ST than in CT. Since 5 to 24% of C accumulation in lint and grain were harvested, C sequestered in cotton and sorghum stalks and roots can be significant in the terrestrial ecosystem and can significantly increase C storage in the soil if these residues are left after lint or grain harvest, thereby helping to mitigate the effects of global warming. Conservation tillage, such as ST, with hairy vetch/rye mixture cover crops and 60-65 kg N ha )1 can sustain C accumulation in cotton lint and sorghum grain and increase C storage in the surface soil due to increased C input from crop residues and their reduced incorporation into the * FAX No: +1-406-433-5038.

Remediation of degraded arable steppe soils in Moldova using vetch as green manure

“…This is in the upper part of the range of observed C sequestration rates in humid regions. In the USA, the incorporation of hairy vetch as green manure in cereal, cotton and vegetable production resulted in a wide range of SOC accumulation of 0.2 to 2.7 t ha −1 yr −1 in topsoils (0 to 30 cm) in the first 3 to 7 years of the experiments (Sainju et al, 2002(Sainju et al, , 2003(Sainju et al, , 2005b. In Japan, C sequestration ranges from 0.6 to 1.0 t ha −1 yr −1 were found in topsoils (0 to 30 cm) by including hairy vetch as cover crop in rice and soybean cultivation under a humid subtropical climate (Higashi et al, 2014).…”

Pathways of soil organic matter formation from above and belowground inputs in a Sorghum bicolor bioenergy crop

“…Additionally, it is unique as an actively researched bioenergy feedstock, because it is grown as an annual crop, thus the entire root system is left to decompose every year. Sorghum root biomass estimates range from ~ 0.5 to 6.1 mg dry matter per ha based on field measurements, to 7 mg dry matter per ha based on modeled projections (Meki, Snider, Kiniry, Raper, & Rocateli, ; Monti & Zatta, ; Sainju, Whitehead, & Singh, ; Schittenhelm & Schroetter, ).…”

Sorghum Biomass Production for Energy Purpose Using Treated Urban Wastewater and Different Fertilization in a Mediterranean Environment

“…Johnston et al [65] reported that application of nitrogen fertilizer increases sorghum culm yield. Sainju et al [66] and Almodares et al [67] reported an increase of biomass production due to nitrogen fertilization. The mycorrhization of plants did not promote significant biomass differences from the unfertilized control treatment in either trial year, whereas in the second year, the mycorrhizal fungi effect was also not statistically different from N fertilized plants (Table 5).…”