• Authors:
    • Munkholm, L. J.
    • Abdollahi, L.
    • Garbout, A.
  • Source: SOIL SCIENCE SOCIETY OF AMERICA JOURNAL
  • Volume: 78
  • Issue: 1
  • Year: 2014
  • Summary: Information about the quantitative effect of conservation tillage combined with a cover crop on soil structure is still limited. This study examined the effect of these management practices on soil pore characteristics of a sandy loam soil in a long-term field trial. The tillage treatments (main plots) included direct drilling (D), harrowing to a depth of 8 to 10 cm (H), and moldboard plowing (MP). The cover crop treatments were subplot with cover crop (+CC) and without cover crop (-CC). Minimally disturbed soil cores were taken from the 4- to 8-, 12- to 16-, and 18- to 27-cm depth intervals in the spring of 2012 before cultivation. Soil water retention and air permeability were measured for matric potentials ranging from -1 to -30 kPa. Gas diffusivity was measured at -10 kPa. Computed tomography (CT) scanning was also used to characterize soil pore characteristics. At the 4- to 8- and 18- to 27-cm depths, pore characteristics did not differ significantly among tillage treatments. At the 12- to 16-cm depth, negative effects of reduced tillage (D and H) were recorded for total porosity and air-filled porosity at -10 kPa (that is, >30-μm pores). Generally, the use of a cover crop increased air-filled porosity at -10 kPa, air permeability, and pore organization and reduced the value of blocked air porosity at all depths for all tillage treatments. Our results show that the cover crop created continuous macropores and in this way improved the conditions for water and gas transport and root growth. The cover crop thus alleviated the effect of tillage pan compaction in all tillage treatments. © Soil Science Society of America.
  • Authors:
    • Basanta, M.
    • Costantini, A.
    • Alvarez, C. R.
    • Alvarez, C.
  • Source: SOIL & TILLAGE RESEARCH
  • Volume: 142
  • Year: 2014
  • Summary: Soil management affects distribution and the stocks of soil organic carbon and total nitrogen. The aim of this study was to evaluate the effect of different crop sequences and tillage systems on the vertical distribution and stocks of soil carbon and nitrogen. We hypothesized that no-tillage promotes surface organic carbon and total nitrogen accumulation, but does not affect the C and N stocks, when compared with reduced tillage. In addition, the incorporation of maize in the crop sequence increases total organic carbon and total nitrogen stocks. Observations were carried out in 2010 in an experiment located in the semiarid Argentine Pampa, on an Entic Haplustoll. A combination of three tillage systems (no tillage, no tillage with cover crop in winter and reduced tillage) and two crop sequences (soybean-maize and soybean monoculture) were assessed. After 15 years of management treatments, soil samples to a depth of 100. cm at seven intervals, were taken and analyzed for bulk density, organic carbon and total nitrogen. Total organic carbon stock up to a depth of 100. cm showed significant differences between soils under different tillage systems (reduced tillage. <. no tillage = no tillage with cover crop), the last ones having 8% more than the reduced tillage treatment. Soybean-maize had 3% more organic C up to 100. cm depth than the soybean monoculture. Total nitrogen stock was higher under no-till treatments than under reduced tillage, both at 0-50 and 0-100. cm depths. Total organic carbon stratification ratios (0-5. cm/5-10. cm) were around 1.6 under no-till and lower under reduced tillage. The stratification ratio explains less than 40% of soil carbon stock. Tillage system had a greater impact on soil carbon stock than crop sequence. © 2014 Elsevier B.V.
  • Authors:
    • Saxton, A. M.
    • Wight, J. P.
    • Allen, F. L.
    • Ashworth, A. J.
    • Tyler, D. D.
    • Sams, C. E.
  • Source: SOIL SCIENCE SOCIETY OF AMERICA JOURNAL
  • Volume: 78
  • Issue: 5
  • Year: 2014
  • Summary: Climate change may be mitigated through soil organic C (SOC) storage under no-tillage; however, crop management influences on SOC are not well defined in all systems. Our objective was to compare long-term C fluxes under two no-tillage sites at Research and Education Centers in Milan (RECM) on Oxyaquic Fragiudalfs and at Middle Tennessee (MTREC) on a Typic Paleudalf in a split-block design with four replications. The whole-block was cropping sequences of corn (Zea mays L.), soybeans [Glycine max (L.) Merr.], and cotton (Gossypium hirsutum L.) with split-block bio-cover treatments of winter wheat (Triticum aestivum L.), hairy vetch [Vicia villosa Roth subsp. villosa], poultry litter, and a fallow control. The same sequences were performed at MTREC without cotton. Soil C flux was calculated at surfaces (0-5 cm) and subsurfaces (5-15 cm) during Year 0, 2, 4, and 8. During the first 2 yr, C losses occurred in all treatments and locations (1.40 and 1.20 Mg ha-1at RECM and MTREC, respectively), with stabilization initiating by Year 4. By Year 8, sequences with high frequencies of soybean and greater temporal complexity gained more surface SOC. Poultry litter bio-covers gained more surface SOC compared to wheat, vetch, and fallow bio-covers (P < 0.05). After 8 yr, surface SOC surpassed initial levels (9.20 and 8.79 Mg ha-1), with mean gains of 1.33 and 1.16 Mg C ha-1at RECM and MTREC, respectively. Losses occurred in subsoils at MTREC and RECM, but by Year 8 several treatments had recovered to near baseline levels. Results suggest surface C storage may be enhanced by crop sequence diversity combined with poultry litter bio-covers in no-till systems, whereas subsurface levels may require more time.
  • Authors:
    • Wienhold, B. J.
    • Schmer, M. R.
    • Jin, V. L.
    • Ferguson, R. B.
    • Blanco-Canqui, H.
    • Tatarko, J.
  • Source: SOIL SCIENCE SOCIETY OF AMERICA JOURNAL
  • Volume: 78
  • Issue: 4
  • Year: 2014
  • Summary: Addition of cover crops and animal manure following corn (Zea mays L.) stover removal for expanded uses may mitigate negative soil property effects of stover removal. We studied the short-Term (3 yr) cumulative impacts of stover removal with and without winter rye (Secale cereale L.) cover crop or animal manure application on near-Surface (0- to 5-cm depth) soil properties under irrigated no-Till continuous corn on a Hastings silt loam (fine, smectitic, mesic Udic Argiustolls) (<3% slope) near Clay Center, NE. Treatments were irrigation levels (full and deficit), amelioration practices (none, cover crop, or animal manure), stover removal (no removal or maximum removal), and N fertilization (125 or 200 kg N ha-1). Data collected after 3 yr indicate that stover removal (63%) reduced geometric mean diameter of dry aggregates 93%, increased erodible fraction sixfold, and reduced aggregate stability 32% compared with plots without stover removal. Stover removal from plots with cover crop or manure reduced dry aggregate size and stability and increased erodible fraction compared with plots without removal and amelioration practices, indicating that amelioration practices did not offset stover removal effects. Stover removal reduced wet aggregate stability and soil organic C (SOC) concentration in the 0- to 2.5-cm depth, but cover crop or manure mitigated these small reductions. Stover removal did not change water infiltration rates and had small effects on particulate organic matter (POM). Overall, in the short term, cover crop or manure may not provide sufficient protection from raindrop impact and wetting and drying cycles to maintain soil structure, resulting in increased susceptibility to wind erosion. Use of these amelioration practices, however, may offset changes in surface layer wet aggregate stability and SOC after high rates of stover removal in this region. © Soil Science Society of America, 5585 Guilford Rd., Madison WI 53711 USA.
  • Authors:
    • Radicetti, E.
    • Di Felice, V.
    • Mancinelli, R.
    • Campiglia, E.
  • Source: SOIL & TILLAGE RESEARCH
  • Volume: 139
  • Year: 2014
  • Summary: There is a lack of information regarding the long-term residual effects of winter cover crops on the following cash crops. Two 2-year field experiments (from 2009 to 2012) were carried out in the Mediterranean environment of Central Italy in a Typic Xerofluvent soil. Endive (Cichorium endivia L.) and savoy cabbage (Brassica oleracea var. sabauda) were grown following a winter cover crop-pepper (Capsicum annum L.) sequence. We hypothesized that some cover crops and their residue management can have a long-term effect on the availability of soil nitrogen. The objectives were to quantify the: (i) nitrogen remaining in the soil and in the residues of cover crops after pepper cultivation; (ii) endive and savoy cabbage response due to the residual effect of cover crop residues, and (iii) mass of inorganic nitrogen required for obtaining a similar effect to that obtained with the residues of cover crops. The treatments consisted in three cover crop species [hairy vetch (Vicia villosa Roth.), oat (Avena sativa L.) and oilseed rape (Brassica napus L.)], three managements of the aboveground biomass of cover crops [incorporated into the soil 30cm depth (conventional tillage, CT), incorporated into the soil 10cm depth (minimum tillage, MT), left on the soil surface in mulch strips (no-tillage, NT)] plus a control without cover (no cover) fertilized with three levels of nitrogen (none, medium, high). At transplant of vegetables, the nitrogen in the cover crop residues ranged from 60kgha-1 in hairy vetch NT to 9kgha-1 in oilseed rape CT, while the soil inorganic nitrogen (NO3-N+NH4-N) was about twice in hairy vetch (20.9+7.4mgkg-1 dry soil, respectively) compared with oat and 1.5 times compared with oilseed rape. The marketable yield of endive and savoy cabbage was approximately tripled in hairy vetch compared to oat, oilseed rape and the unfertilized control (20.4 and 18.6 vs. 6.7 and 5.2tha-1 of FM, respectively). The endive and savoy cabbage yield was higher in NT and MT than in CT hairy vetch and similar to no cover fertilized with 50 and 75kgha-1 of N, respectively. Results confirm the hypothesis that some cover crops, such as hairy vetch, can have a long-term effect on the availability of soil nitrogen which exceeds the cultivation period of the following summer vegetable crop and can be profitably used by a second cash crop transplanted in close sequence. © 2014 Elsevier B.V.
  • 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:
    • 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:
    • Deichman, C. L.
    • Kremer, R. J.
  • Source: AGRONOMY JOURNAL
  • Volume: 106
  • Issue: 5
  • Year: 2014
  • Summary: The solar corridor crop system (SCCS) is designed for improved crop productivity based on highly efficient use of solar radiation by integrating row crops with drilled or solid-seeded crops in broad strips (corridors) that also facilitate establishment of cover crops for year-round soil cover. The SCCS is an agroecosystem with diverse system structure that should inherently provide many features to build soil quality. Management strategies include reduced tillage, intercropping, and soil conservation through crop residue retention, which are associated with improved soil quality attributes of enhanced C and N content, effective nutrient cycling, and high microbial activity. Our objective was to evaluate the effect of SCCS in 76- and 152-cm (corridor) row widths on selected soil quality indicators as an assessment of soil quality during establishment of SCCS. Microbial activity, measured as soil glucosidase activity, was highest in rhizosphere soils planted to corn ( Zea mays L.) hybrids at 74,000 plants ha -1 regardless of row width. However, soil glucosidase activity was strongly correlated ( r2=0.72) with active carbon (AC), and showed trends for increased contents in rows bordering the corridor. This suggested that increased carbon fixation by plants at the wide row spacing due to greater exposure to solar radiation also increased carbon substrates released into the rhizosphere for microbial metabolism. The limited soil quality assessment conducted in this study demonstrated that an integrated cropping system represented by the SCCS offers an effective management system for maintaining crop production while promoting soil quality and soil conservation.
  • Authors:
    • Baffaut, C.
    • Veith, T. L.
    • Moore, M. T.
    • Potter, T. L.
    • Bryant, R. B.
    • Lizotte, R. E.
    • Sadler, E. J.
    • Tomer, M. D.
    • Locke, M. A.
    • Walbridge, M. R.
  • Source: JOURNAL OF SOIL AND WATER CONSERVATION
  • Volume: 69
  • Issue: 5
  • Year: 2014
  • Summary: Ten years ago, the USDA Agricultural Research Service (ARS) began a series of watershed assessment studies as part of the Conservation Effects Assessment Project (CEAP). In this overview, a decade of research progress in 14 watersheds dominated by rain-fed croplands is reviewed to introduce a special section of this journal issue containing papers describing multiwatershed syntheses. The papers evaluate impacts of agricultural practices on soil quality, stream sediment sources, and the role of climate variability in watershed studies and conservation assessments at the watershed scale. The cross-watershed comparisons help enhance our understanding of emerging conservation technologies in terms of their readiness and suitability for wide-scale adoption. Research from ARS CEAP watershed assessments published during the past 10 years suggests encouraging (1) wider adoption of minimum disturbance technologies to reduce runoff risks associated with applying manure, nutrients, and agrichemicals; (2) adoption of winter cover crops; and (3) a renewed emphasis on riparian corridors to control loads of sediment, phosphorus (P), and other contaminants originating from within (and near) stream channels. The management of agricultural watersheds requires that watershed-scale data can be interpreted and applied in management at the farm scale, and that farm-scale information, including financial and management constraints, can be used to clarify watershed management opportunities and challenges. Substantial research needs remain, including social engagement of agricultural communities, use of multiple conservation practices to account for environmental tradeoffs, improved models to simulate the dynamics of nutrient retention and movement in watersheds, and understanding ecosystem responses to changes in water quality. Moreover, a long-term commitment to understand land use trends, water quality dynamics, climate impacts, and the real effectiveness of precision conservation approaches for improving water quality will help secure agriculture's capacity to provide food, water, and other ecosystem services vital to society.
  • Authors:
    • Taboada, M. A.
    • Scianca, C. M.
    • Varela, M. F.
    • Rubio, G.
  • Source: SOIL & TILLAGE RESEARCH
  • Volume: 143
  • Year: 2014
  • Summary: Cover crops (CC) provide many benefits to soils but their effect on decomposition of previous crop residues and release of nutrients in continuous no-tillage soybean [Glycine max (L.) Merr.] production are little known. Our objective was to quantify CC effects on decomposition and phosphorus (P) release from soybean residue using litterbags. Three CC species (oat, Avena sativa L.; rye, Secale cereal L.; and rye grass, Lolium multiflorum L.) and a no CC control were evaluated. Temperature, moisture content, microbial biomass and microbial activity were measured in the surface 2cm of soil and residues. Cover crops increased soybean residue decomposition slightly both years (8.2 and 6.4%). Phosphorus release from soybean residue did not show any significant differences. Cover crops increased microbial biomass quantity and activity in both soil and residue samples (p<0.001, p=0.049 for soil and residue microbial biomass; p=0.060, p=0.003 for soil and residue microbial activity, respectively). Increased residue decomposition with CC was associated with higher soil and residue microbial biomass and activity, higher near-surface (0-2cm) moisture content (due to shading) and soil organic carbon enrichment by CC. Even though CC increased soybean residue decomposition (233kgha-1), this effect was compensated for by the annual addition of approximately 6500kgha-1 of CC biomass. This study demonstrated another role for CC when calibrating models that simulate the decomposition of residues in no-tillage systems.