• Authors:
    • Franzluebbers, A. J.
    • Stuedemann, J. A.
  • Source: SOIL SCIENCE SOCIETY OF AMERICA JOURNAL
  • Volume: 78
  • Issue: 4
  • Year: 2014
  • Summary: Soil organic C and N are important indicators of agricultural sustainability, yet numerous field studies have revealed a multitude of responses in the extent and rate of change imposed by conservation management and, therefore, a lack of clarity on responses. We conducted an evaluation of total and particulate organic C and N in the surface 30 cm on a Typic Kanhapludult in northern Georgia during 7 yr of tillage (conventional disk and no tillage) and cover crop utilization (ungrazed and grazed by cattle). Soil organic C and total soil N were greater under no tillage (NT) than under conventional tillage (CT) at depths of 0 to 3 and 3 to 6 cm but were lower under NT than CT at depths of 12 to 20 and 20 to 30 cm. Total soil N accumulated with time at a depth of 0 to 6 cm under both tillage systems and the rate tended to be greater under NT than under CT (0.039 vs. 0.021 Mg N ha-1 yr -1, p = 0.10). Soil organic C accumulated with time at a depth of 0 to 6 cm under all management systems, but there was a significant tillage × cover crop interaction (0.68 and 1.09 Mg C ha-1 yr -1 with ungrazed cover crop management under CT and NT, respectively, and 0.84 and 0.66 Mg C ha-1 yr-1 with grazed cover crop management under CT and NT, respectively). At a depth of 0 to 30 cm, there was only a tillage trend (1.00 and 1.59 Mg C ha-1 yr-1 under CT and NT, respectively; p = 0.09). Particulate organic C was more dramatically different than soil organic C between tillage regimes at a depth of 0 to 30 cm (-0.49 and 0.35 Mg C ha-1 yr-1 under CT and NT, respectively; p < 0.001). Grazing of cover crops had little negative impact on soil C and N fractions, suggesting that NT and grazing of cover crops could provide a broader-spectrum conservation cropping approach in the southeastern United States. © Soil Science Society of America, 5585 Guilford Rd.
  • Authors:
    • Al-Kaisi, M. M.
    • Guzman, J. G.
  • Source: SOIL SCIENCE SOCIETY OF AMERICA JOURNAL
  • Volume: 78
  • Issue: 2
  • Year: 2014
  • Summary: Agriculture management practices can significantly affect soil C storage through changes in C inputs and losses. This study investigated the shortterm effects of tillage (no-tillage [NT] and conventional tillage [CT]), residue removal (0, 50, and 100%), and N rates of 0, 170, and 280 kg N ha-1 on soil C storage. Studies were established in 2008 to 2011 on a Nicollet clay loam (fine-loamy, mixed superactive, mesic Aquic Hapludolls) and Canisteo clay loam (Fine-loamy, mixed, superactive, calcareous, mesic Typic Endoaquolls) soil association at Ames, central Iowa site (AC) and a Marshall silty clay loam (Fine-silty, mixed, superactive, mesic Typic Hapludolls) soil association at Armstrong, southwest Iowa site (ASW) in continuous corn (Zea Mays L.). Findings from the C budget show that under CT and N rate of 170 kg N ha-1 in continuous corn, there was no significant change in net soil C with no residue removal. Increasing N rate from 170 to 280 kg N ha-1 resulted in greater potential C inputs from above and belowground biomass, although C losses were not significantly different, especially with NT. Thus, a portion of soil surface residue could be removed without causing a net loss of soil C. Converting from CT to NT led to lower soil C losses, but C inputs varied due to soil temperature and water content differences and seasonal variability in a given year. Consequently, averaged across both tillage systems and at 280 kg ha-1 N rate for continuous corn approximately 5.10 and 4.18 Mg ha-1 of the residue should remain on the field to sustain soil C in 2010 and 5.23 and 5.18 Mg ha-1 in 2011 for AC and ASW sites, respectively. These finding suggest that residue removal needs to be approached on yearly basis with particular consideration to site's yield potential and weather condition as the residue biomass production can be variable. © Soil Science Society of America.
  • Authors:
    • Kaneko, N.
    • Araki, H.
    • Hirata, T.
    • Miura, S.
    • Komatsuzaki, M.
    • Yunghui, M.
    • Higashi, T.
    • Ohta, H.
  • Source: SOIL & TILLAGE RESEARCH
  • Volume: 138
  • Year: 2014
  • Summary: No-tillage, cover crops, and N fertilization play important roles in conserving or increasing soil organic carbon (SOC). However, the effects of their interaction are less well known, particularly in Asian countries. We examined the effects of three tillage management systems, moldboard plow/rotary harrow (MP), rotary cultivator (RC), and no-tillage (NT); three winter cover crop types (FL: fallow, RY: rye, and HV hairy vetch); and two nitrogen fertilization rates (0 and 100kgNha-1 for upland rice and 0 and 20kgNha-1 for soybean production) on changes in SOC. Vertical distributions at 0-2.5, 2.5-7.5, 7.5-15, and 15-30cm depths of soil carbon content and bulk density were measured each year. From 2003 to 2011, NT and RC management increased SOC by 10.2 and 9.0Mgha-1, whereas SOC under the MP system increased only by 6.4Mgha-1. Cover crop species also significantly increased SOC in the same period by 13.4 and 8.6Mgha-1 for rye and hairy vetch, respectively, although SOC with fallow increased only by 5.4Mgha-1. Continuous soil management for 9 years enhanced SOC accumulation. Summer crop species between upland rice and soybean strongly affected SOC; the SOC increases were 0.29Mgha-1year-1 for the upland rice rotation and 1.84Mgha-1year-1 for the soybean rotation. However, N fertilization levels did not significantly affect SOC. These results suggest that the NT system and rye cover crop enhance carbon sequestration in Kanto, Japan, but that their contributions differ depending on the combination of main and cover crops. © 2014 .
  • Authors:
    • Li, H.
    • Li, Y.
    • Wilson, G. V.
    • Ouyang, Z.
    • Hou, R.
  • Source: SOIL SCIENCE SOCIETY OF AMERICA JOURNAL
  • Volume: 78
  • Issue: 1
  • Year: 2014
  • Summary: Differences in soil organic carbon (SOC) distribution, water holding capacity, and soil temperature between no-tillage (NT) and conventional tillage (CT) systems can result in different soil CO2 emissions which could affect global warming but few studies have addressed this concern. An open warming experiment was conducted in situ by infrared heating of longterm conservation tillage management plots in North China Plain (NCP) to determine the effects of warming on soil CO2 emissions and the correlation to changes in soil temperature and moisture. This experiment was conducted from February 2010 to June 2012 and included CT and NT plots with and without warming. Warming treatment increased soil temperature by 2.1 and 1.5°C, and decreased volumetric soil-water content by 14 and 10% for CT and NT systems, respectively. Soil CO2 emissions tended to decrease with time in CT while it consistently increased in NT system over the three wheat seasons and two maize seasons under warming. Our results suggest that differences in soil temperature and soil moisture between the two tillage systems could be enlarged with time by warming, and the potential exist for warming to promote more soil CO2 emission under NT relative to CT. There is a need to consider the differences in response to global warming between these two tillage systems to properly assess the benefits of NT to C sequestration.
  • Authors:
    • Osmond, D.
    • Hoyt, G.
    • Edgell, J.
    • Grossman, J.
    • Larsen, E.
    • Hu, S.
  • Source: SOIL & TILLAGE RESEARCH
  • Volume: 139
  • Year: 2014
  • Summary: Topsoil losses through surface runoff have severe implications for farmers, as well as surrounding ecosystems and waterbodies. However, integrating management systems that enhance soil organic matter (SOM) can stabilize the soil surface from erosion. Little is known about how differences in both tillage and cropping system management affect carbon and subsequent sediment losses in horticultural fields, particularly in the humid climate of the southeast. Research was conducted in the Appalachian Mountains in Mills River, NC on a fine-sandy loam Acrisol from 2010 to 2012 on long-term plots established in 1994. Project objectives included to: (1) quantify labile and total organic matter based on tillage and cropping system practices, (2) determine if relationships exist between SOC ad sediment losses, and (3) determine long-term management and tillage impacts on total organic matter lost via runoff. We hypothesized that organic management and reduced tillage would lead to increased soil carbon, which subsequently reduce losses as soil is stabilized. Organic no tillage and conventional till treatments contained on average 14.34 and 6.80gkg-1 total carbon (TC) respectively, with the organic no till treatments containing twice the quantity of TC and light fraction particulate organic matter (LPOM) in the upper 15cm as compared with the conventionally tilled treatments, and four times the quantity of microbial biomass carbon (MBC). LPOM and HPOM, the heavier fraction of POM, did not differ in the organic till and conventional no till treatments.Data support our hypothesis that organic production in combination with no tillage increases C pools (both total and labile) as compared with tilled conventional plots. However, organic no till treatments produced sweet corn (Zea mays var. saccharata) yields less than 50% of that of conventional treatments, attributed to weed competition and lack of available N. No tillage treatments lost two to four times less soil C via surface runoff than tilled systems. Additionally, we found that as total soil C increased, suspended solids lost through surface runoff decreased. Overall, our results indicate tillage to be an important factor in enhancing soil C and decreasing soil loss through surface runoff. © 2014 Elsevier B.V.
  • Authors:
    • Venterea, R. T.
    • Maharjan, B.
  • Source: JOURNAL OF ENVIRONMENTAL QUALITY Pages:
  • Volume: 43
  • Issue: 5
  • Year: 2014
  • Summary: Anhydrous ammonia (AA) is a major fertilizer source in North America that can promote greater emissions of nitrous oxide (N 2O) than other nitrogen (N) fertilizers. Previous studies found that injection of AA at a shallow depth (0.1 m) decreased N 2O in a rainfed clay loam but increased N 2O in an irrigated loamy sand compared with the standard injection depth of 0.2 m. The objective of this study was to evaluate the effects of AA injection depth in a silt loam soil used for corn ( Zea mays L.) production and managed under two contrasting tillage regimes over two consecutive growing seasons (2010 and 2011) in Minnesota. In contrast with previous studies, AA placement depth did not affect N 2O emissions in either tillage system or in either growing season. Tillage by itself affected N 2O emissions only in the drier of two seasons, during which N 2O emissions under no tillage (NT) exceeded those under conventional tillage (CT) by 55%. Soil moisture content under NT was also greater than under CT only in the drier of the two seasons. Effects of AA placement depth and long-term tillage regime on N 2O emissions exhibit intersite as well as interannual variation, which should be considered when developing N 2O mitigation strategies. Further study is needed to identify specific soil, climate, or other factors that mediate the contrasting responses to management practices across sites.
  • Authors:
    • Kaspar, T. C.
    • Wiedenhoeft, M. H.
    • Moore, E. B.
    • Cambardella, C. A.
  • Source: SOIL SCIENCE SOCIETY OF AMERICA JOURNAL
  • Volume: 78
  • Issue: 3
  • Year: 2014
  • Summary: Corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] farmers in the upper Midwest are showing increasing interest in winter cover crops. The effects of winter cover crops on soil quality in this region, however, have not been investigated extensively. The objective of this experiment was to determine the effects of a cereal rye (Secale cereale L.) winter cover crop after more than 9 yr in a corn silage-soybean rotation. Four cereal rye winter cover crop treatments were established in 2001: no cover crop, rye after soybean, rye after silage, and rye after both. Soil organic matter (SOM), particulate organic matter (POM), and potentially mineralizable N (PMN) were measured in 2010 and 2011 for two depth layers (0-5 and 5-10 cm) in both the corn silage and soybean phases of the rotation. In the 0- to 5-cm depth layer, a rye cover crop grown after both main crops had 15% greater SOM, 44% greater POM, and 38% greater PMN than the treatment with no cover crops. In general, the treatments that had a rye cover crop after both crops or after corn silage had a positive effect on the soil quality indicators relative to treatments without a cover crop or a cover crop only after soybean. Apparently, a rye cover crop grown only after soybean did not add enough residues to the soil to cause measureable changes in SOM, POM, or PMN. In general, rye cover crop effects were most pronounced in the top 5 cm of soil.
  • Authors:
    • Silva, W. T. L. D.
    • Cerri, C. E. P.
    • Nogueirol, R. C.
    • Alleoni, L. R. F.
  • Source: SOIL & TILLAGE RESEARCH
  • Volume: 143
  • Year: 2014
  • Summary: The effects of organic matter on soil properties depend on its content and quality. Understanding the carbon dynamics and soil organic matter (SOM) quality is crucial for evaluating the sustainability of agricultural systems, the global carbon cycle, elemental weathering, and soil capacity to withstand physical damage. The objective of this study was to assess SOM quality in four Brazilian locations, two of them under no-till (NT) conditions in which soils were amended with lime and gypsum, and the other two soils amended with sewage sludge or compost under conventional system. Soil samples were collected at a depth of 0-0.1. m in four long-term field experiments: (i) a NT system with limestone amendment and re-amendment; (ii) a NT system with gypsum amendment and re-amendment; (iii) a soil amended with sewage sludge for 13 consecutive years; and (iv) a soil amended with just one sewage sludge and composted sludge. Physical and chemical fractionation of SOM and analyzed samples were performed by laser-induced fluorescence (LIF; soil) and nuclear magnetic resonance (NMR; HS). In addition, the Carbon Management Index (CMI) was calculated to evaluate the impacts of soil management practices on organic matter quality. The highest carbon content was found in the free light organic fraction in all experiments, followed by the silt. +. clay fraction. NMR detected predominance of the C-alkyl and C. O-alkyl organic radicals. Both fluorescence and LIF techniques generated Humification Indexes with similar trend. There were differences between the experimental sites when SOM granulometric fractions were analyzed, but no differences in the predominant organic compounds were observed. Soil quality, assessed by CMI, was generally improved with limestone, gypsum, compost and sludge.
  • Authors:
    • Lal, R.
    • Al-Kaisi, M. M.
    • Olson, K. R.
    • Lowery, B.
  • Source: SOIL SCIENCE SOCIETY OF AMERICA JOURNAL
  • Volume: 78
  • Issue: 2
  • Year: 2014
  • Summary: In agricultural land areas, no-tillage (NT) farming systems have been practiced to replace intensive tillage practices such as, moldboard plow (MP), chisel plow (CP), and other systems to improve many soil health indicators, and specifically to increase soil organic carbon (SOC) sequestration and reduce soil erosion. Numerous approaches to estimate the amounts and rates of SOC sequestration as a result of a switch to NT systems have been published, but there is a concern regarding protocol for assessing SOC especially for different tillage systems. Therefore, the objectives of this paper are to: (i) define and understand concepts of SOC sequestration, (ii) quantify SOC distribution and the methodology of measurements, (iii) address soil spatial variability at field- or landscape-scale for potential SOC sequestration, and (iv) consider proper field experimental design, including pretreatments baseline for SOC sequestration determination. For SOC sequestration to occur, as a result of a treatment applied to a land unit, all of the SOC sequestered must originate from the atmospheric CO2 pool and be transferred into the soil humus through land unit plants, plant residues, and other organic solids. The SOC stock present in soil humus at end of a study must be greater than the pretreatment SOC stock levels in the same land unit. However, one should recognize that a continuity equation showing drawdown in atmospheric concentration of CO2 may be difficult, if not impossible, to quantify. Therefore, SOC sequestration results of paired comparisons of NT to other conventional tillage systems with no pretreatments SOC baseline, and if the conventional system is not at a steady state, will likely be inaccurate where the potential for SOC loss exists in both systems. To unequivocally demonstrate that the SOC sequestration has occurred at a specific site, a temporal increase must be documented relative to pretreatment SOC content and linked attendant changes in soil properties and ecosystem services and functions with proper consideration given to soil spatial variability. Also, a standardized methodology that includes proper experimental design, pretreatment baseline, root zone soil depth consideration, and consistent method of SOC analysis must be used when determining SOC sequestration.
  • Authors:
    • Adhya, T. K.
    • Singh Bohra, J.
    • Agrawal, M.
    • Pandey, D.
    • Bhattacharyya, P.
  • Source: SOIL & TILLAGE RESEARCH
  • Volume: 143
  • Year: 2014
  • Summary: In order to utilize agricultural soils as an option to offset atmospheric carbon, it is essential to ascertain the degree of stability of the accrued carbon. A two step acid hydrolysis technique was used to separate labile and recalcitrant carbon pools in soil upto 30cm depth to analyze their responses to different tillage managements after eight years of continuous practice in a sub-humid tropical rice-wheat system of Indo-Gangetic plains. There were four tillage practices; tillage before sowing/transplantation of every crop (RCT-WCT), tillage before transplanting of rice but no tillage before sowing the succeeding wheat crop (RCT-WNT), tillage before sowing of wheat but no tillage before sowing of rice (RNT-WCT), and no tillage before sowing of rice as well as wheat (RNT-WNT). It was observed that reduction in tillage frequency enhanced the total and recalcitrant carbon contents in soil with the maximum rate of sequestration recorded under RNT-WNT (0.59tCha-1yr-1). The fraction of carbon translated into recalcitrant pool was constant under all the tillage combinations indicating that carbon stabilization was dependent predominantly on organic matter input in the rice-wheat system. Conventional tillage on the other hand caused loss of carbon from the soil as observed by reduction in total soil carbon content under RCT-WCT. Reduction in recalcitrant carbon content under RCT-WCT further indicated that acid hydrolysis might not represent long term carbon accumulation reliably. Concentration of phenolics in labile pool increased under RNT-WNT, RCT-WNT and RNT-WCT practices which also had higher total and recalcitrant carbon pools. This indicated towards contribution of phenolics in carbon stabilization in the soil. Results of the present study further suggested that adoption of no till agriculture in the region offers significant carbon sequestration opportunity under proper agricultural management.