• Authors:
    • Higarashi, M. M.
    • Oliveira, P. A. V. de
    • Denega, G. L.
    • Bayer, C.
    • Silveira Nicoloso, R. da
    • Correa, J. C.
    • Santos Lopes, L. dos
  • Source: Ciencia Rural
  • Volume: 43
  • Issue: 2
  • Year: 2013
  • Summary: Assessments of soil carbon dioxide (CO 2), methane (CH 4), and nitrous oxide (N 2O) emissions are critical for determination of the agricultural practices' potential to mitigate global warming. This study evaluated the photoacoustic spectroscopy (PAS) for the assessment of soil greenhouse gases (GHG) fluxes in comparison to the standard gas chromatography (GC) method. Two long-term experiments with different tillage and cropping systems over a Paleudult were evaluated using static chambers. PAS measurements of CO 2 and N 2O concentrations showed good relationship and linearity (R 2=0.98 and 0.94, respectively) with GC results. However, CH 4 measurements were significantly affected by air sample moisture which interfered on CH 4 detection by PAS. Overestimation of CO 2 and N 2O concentrations in air samples determined by PAS (14.6 and 18.7%, respectively) were also related to sampling moisture. CO 2 and N 2O fluxes showed good agreement between methods (R 2=0.96 and 0.95, respectively), though PAS overestimated fluxes by 18.6 and 13.6% in relation to GC results, respectively. PAS showed good sensitivity and was able to detect CO 2 and N 2O fluxes as low as 332 mg CO 2 m -2 h -1 and 21g N 2O m -2 h -1. PAS analyzer should be detailed calibrated to reduce humidity interference on CO 2, CH 4 and N 2O concentrations measurements avoiding overestimation or erroneous determination of soil GHG fluxes.
  • Authors:
    • Petersen,Soren O.
    • Schjonning,Per
    • Olesen,Jorgen E.
    • Christensen,Soren
    • Christensen,Bent T.
  • Source: Soil Science Society of America Journal
  • Volume: 77
  • Issue: 1
  • Year: 2013
  • Summary: In organic cropping systems, legumes, cover crops (CC), residue incorporation, and manure application are used to maintain soil fertility, but the contributions of these management practices to soil nitrogen (N) supply remain obscure. We examined potential sources of N for winter wheat (Triticum aestivum L.) in four experimental cropping systems established in 1997 on three soil types. Three of the four systems were under organic management. Topsoil N, depth of the A horizon, and cumulated inputs of N since 1997 were determined at plot level. Labile soil N pools [mineral N, potentially mineralizable N (PMN), microbial biomass N (MBN)] were monitored during two growth periods; at one site, biomass C/N ratios were also determined. Soil for labile N analysis was shielded from N inputs during spring application to isolate cumulated system effects. Potentially mineralizable N and MBN were correlated across all sites and rotations (r(2) = 0.72). The MBN corresponded to 46 to 85, 85 to 145, and 74 to 172 kg N ha(-1) at the three sites and differed significantly between cropping systems, but MBN could not explain differences in wheat grain N yields. Instead, a multiple linear regression model explained 76 and 82% of the variation in grain N yields in organic cropping systems in 2007 and 2008, showing significant effects of, respectively, topsoil N, depth of A horizon, cumulated inputs of N, and N applied to winter wheat in manure. Thus, soil properties and past and current management all contributed to winter wheat N supply.
  • Authors:
    • da Silva, P. B.
    • Wendling, B.
    • Cardoso, M. M.
    • Kondo, M. K.
    • Brant Albuquerque, C. J.
  • Source: Bioscience Journal
  • Volume: 28
  • Issue: 1
  • Year: 2012
  • Summary: The objective of this work was evaluated the physical attributes of soil and the main agronomic characteristics of sorghum for grain in no-tillage under different vegetation cover. The experiment was conducted during two growing seasons. In the first years were sown seven grass species in intercropping with sorghum for pasture establishment and the sorghum single defining the eight treatments. In the second season, when direct sowing of sorghum, forages available in the trial were previously desiccated for no-till sorghum. The areas representing the tillage had been barred again. In relation to soil physical properties, experiments were conducted under a randomized block design in factorial 8 (treatments) x 3 (depths) with four replications. Data related to the agronomic characteristics of the sorghum experiment was conducted in a randomized block design with four replications. It concluded with the work that the various forages used in the formation of vegetation for no-tillage affects both soil physical properties such as grain yield of sorghum.
  • Authors:
    • Kornecki, T. S.
    • Price, A. J.
    • Arriaga, F. J.
  • Source: HortScience
  • Volume: 47
  • Issue: 2
  • Year: 2012
  • Summary: A field experiment was conducted in Cullman, AL, to evaluate the effects of three different rollers/crimpers on the termination of a rye ( Secale cereale L) winter cover crop, soil moisture, and yield of sweet corn ( Zea mays saccharata L.) in a no-till system. The following roller types were tested: a straight bar roller, a smooth roller with crimper, and a two-stage roller. These rollers were tested at operating speeds of 3.2 km.h -1 and 6.4 km.h -1. The three rollers/crimpers were compared with a smooth drum roller (no crimping bars) plus glyphosate applied at rate 1.0 kg.ha -1 used as a control. Rye termination dates were selected to be 3 weeks before the recommended sweet corn planting date, which is in the beginning of May for this region. Data indicate that at 3 weeks after rolling for all seasons (2006-2008), 100% rye termination was reached with the smooth drum roller and glyphosate. Two weeks after rolling, average rye termination rates by rollers/crimpers alone were 54.6%, 30.0%, and 50.4% in 2006, 2007, and 2008, respectively. Three weeks after rolling, rye termination rates increased only by ~10% compared with 2 weeks after rolling. These termination levels were below the recommended rate of 90% termination necessary for planting a cash crop into the cover residue. Lower rye termination was probably caused by rolling the rye in an early growth stage (flowering stage). The rollers' operating speed did not influence rye termination rates. Similarly, roller type did not affect soil moisture during the first and second week after rolling. Applying glyphosate with rolling did not increase yield of sweet corn in any of the three growing seasons, and in 2006, sweet corn yield was lower compared with the roller alone treatments. These results are important to vegetable organic systems, in which use of herbicides is not allowed. No significant difference in sweet corn yield was found between operating speeds of 3.2 km.h -1 vs. 6.4 km.h -1 and between the assigned treatments in all growing seasons. However, significant differences in sweet corn yield were detected between the years, most likely as a result of different weather patterns. The lowest sweet corn yield of 3513 kg.ha -1 was reported in 2007 as a result of severe drought in spring and summer of 2007. The highest yield of 15,613 kg.ha -1 was recorded in 2006. In 2008, the yield was 10,158 kg.ha -1. Although the different roller designs were not as effective in ending the rye cover crop compared with the glyphosate treatment, sweet corn yields were unaffected. Multiple rolling operations over the same area could be useful if greater rye termination levels are required without the use of a herbicide, but this recommendation should be tested experimentally in more detail.
  • Authors:
    • Luna, J. M.
    • Mitchell, J. P.
    • Shrestha, A.
  • Source: Renewable Agriculture and Food Systems
  • Volume: 27
  • Issue: 1
  • Year: 2012
  • Summary: Organic farming has been historically dependent on conventional tillage operations to convert perennial pasture leys to annual crop rotations, incorporate crop residues, compost and cover crops, as well as to mechanically kill existing vegetation. Conventional tillage, however, has long been known to lead to soil degradation and erosion. A recently developed no-till organic production system that uses a roller-crimper technology to mechanically kill cover crops was evaluated in two states in the western United States. In Washington, pumpkins ( Cucurbita spp.) grown in a no-till roller-crimper (NT-RC) system produced yields 80% of conventional tillage, but with fewer weeds. However, in California on-farm research trials in organic cotton ( Gossypium barbadense L.), tomato ( Lycopersicon esculentum Mill.), eggplant ( Solanum melongena L.) and cowpea ( Vigna unguiculata (L.) Walp.), the no-till system produced virtual crop failure, or yields less than 20% of the standard production method. The major problems associated with rolled cover crops in California included reduced crop seedling emergence, planter impediment with excessive residue, lack of moisture and delay in transplanting of vegetable crops due to continued growth of cover crops, in-season crop competition from cover crop regrowth and impracticability of using cultivators. Further, excessive dry residue during summer in California can present the risk of fire. In both California and Oregon, considerable success has been demonstrated with zone tillage (strip tillage) in conventionally produced field and vegetable crops. In a replicated Oregon trial, the organic strip tillage treatment produced 85% of the broccoli ( Brassica oleracea L.) yield compared to a conventional tillage treatment. Our studies suggest that the zone tillage concept may offer opportunities to overcome many of the agronomic challenges facing no-till.
  • Authors:
    • Mailapalli, D. R.
    • Horwath, W. R.
    • Wallender, W. W.
    • Burger, M.
  • Source: Journal of Irrigation and Drainage Engineering
  • Volume: 138
  • Issue: 1
  • Year: 2012
  • Summary: Development of best management practices (BMPs) such as conservation tillage and winter cover crop to mitigate runoff and reduce dissolved chemicals in irrigation runoff is an important objective for controlling surface water pollution attributable to agricultural activities. In this study, the effect of standard tillage (ST), ST with winter cover cropping (STCC), and no-till (NT) management practices on infiltration, runoff, and dissolved organic carbon (DOC) export from furrow-irrigated fields of 244-m length was investigated for summer 2007 and 2008 irrigations. The practices were implemented for 2 years. The average surface residue cover was 11, 44, and 32% for ST, STCC, and NT, respectively, for 2007 and 11, 59, and 61%, respectively, in the following year of the study. Two irrigations in each year were considered for the analysis. The runoff samples were collected from each tillage treatment using ISCO autosamplers at regular time intervals. The infiltration and runoff were estimated using a volume balance model (VBM) by considering a 0.2-m irrigation requirement. Converting from ST to STCC increased the infiltration by 14 and 43% and reduced the runoff by 48 and 43% in 2007 and 2008 irrigations, respectively; whereas, converting ST to NT enhanced the infiltration by 4% in both years and decreased the runoff by 19 and 23% in 2007 and 2008 irrigations, respectively. The authors observed only slightly higher DOC concentrations in STCC, but there was a 24% increase for NT in 2007 irrigations, and both compared to with ST ranged from 3.98 to 5.46 mg/L. The DOC concentration was not significantly different among the treatments in 2008 irrigations (3.48 to 4.6 mg/L). Combining the runoff and DOC concentration effects, the DOC export for STCC was decreased by 55% in both years; whereas, it was decreased by 4 and 27% for NT in 2007 and 2008 irrigations, respectively, compared with ST. Although STCC and NT have higher concentrations, the reduction in export in these treatments is attributable to lower runoff. These results suggest that DOC export can be controlled with STCC practice. No-till showed the same trend, although these results must be confirmed after extended implementation of this practice.
  • Authors:
    • Weber, D.
    • Way, T. R.
    • Camargo, G. G.
    • Mirsky, S. B.
    • Ryan, M. R.
    • Curran, W. S.
    • Teasdale, J. R.
    • Maul, J.
    • Moyer, J.
    • Grantham, A. M.
    • Spargo, J. T.
  • Source: Renewable Agriculture and Food Systems
  • Volume: 27
  • Issue: 1
  • Year: 2012
  • Summary: Organic producers in the mid-Atlantic region of the USA are interested in reducing tillage, labor and time requirements for grain production. Cover crop-based, organic rotational no-till grain production is one approach to accomplish these goals. This approach is becoming more viable with advancements in a system for planting crops into cover crop residue flattened by a roller-crimper. However, inability to consistently control weeds, particularly perennial weeds, is a major constraint. Cover crop biomass can be increased by manipulating seeding rate, timing of planting and fertility to achieve levels (>8000 kg ha -1) necessary for suppressing summer annual weeds. However, while cover crops are multi-functional tools, when enhancing performance for a given function there are trade-off with other functions. While cover crop management is required for optimal system performance, integration into a crop rotation becomes a critical challenge to the overall success of the production system. Further, high levels of cover crop biomass can constrain crop establishment by reducing optimal seed placement, creating suitable habitat for seed- and seedling-feeding herbivores, and impeding placement of supplemental fertilizers. Multi-institutional and -disciplinary teams have been working in the mid-Atlantic region to address system constraints and management trade-off challenges. Here, we report on past and current research on cover crop-based organic rotational no-till grain production conducted in the mid-Atlantic region.
  • Authors:
    • Penha, L.
    • Khatounian, C.
    • Fonseca, I.
  • Source: Planta Daninha
  • Volume: 30
  • Issue: 1
  • Year: 2012
  • Summary: Weed control has always been an important issue in agriculture. With the advent of no-till systems, soil erosion was reduced but herbicide use was increased. Organic no-till systems try to adjust reduced erosion to the no use of herbicides. Nevertheless, this adjustment is limited by the cost of mechanical weed control. This cost may be reduced by improved cultural weed control with cover crops mulches. In this paper we report a study on the application of compost manure on an oats winter cover crop, preceding soybean, instead of on the soybean summer crop. Treatments comprised a control without compost manure, and compost manure doses of 4 and 8 Mg ha -1 applied either on oats in winter or soybean in summer, organized in a randomized block design, with five replications. In summer, plots were split into weed-controlled or not controlled subplots. The timing of application and the manure doses did not affect the oats biomass or the soybean performance. However, in summer, without water stress, the application of manure at 8 Mg ha -1 directly on soybean has reduced weed biomass in this crop.
  • Authors:
    • Kornecki, T. S.
    • Place, G. T.
    • Reberg-Horton, S. C.
    • Grossman, J. M.
    • Meijer, A. D.
    • Price, A. J.
    • Webster, T. M.
  • Source: Renewable Agriculture and Food Systems
  • Volume: 27
  • Issue: 1
  • Year: 2012
  • Summary: Organic systems in the southeastern USA offer unique challenges and solutions to crop production due to regional soil and climate characterized by highly weathered soil types, high precipitation and the capacity to grow cover crops in the winter. Recently, the interest of producers and researchers in high-residue cover crops and conservation tillage systems has increased. Various designs of the roller-crimper to manage cover crops have been invented and demonstrated to growers in the southeastern region of the USA over the past 17 years. The impacts of high-residue cover crop mulches on the agronomic systems in the region are diverse. Legume cover crops assist with meeting N demand from cash crops though they decompose rapidly and are seldom sufficient for N demanding crops such as corn. Cereal cover crop mulches can have the opposite effect by immobilizing N and have a longer impact on soil moisture and weed dynamics. While undesirable for many crops, N immobilization is one possible mechanism for weed suppression in legume cash crops planted into cereal residues. Other cover crop weed suppression mechanisms include physical impedance, light availability, allelopathy and microclimate effects. Regardless of the cause, successful weed control by mulches is highly dependent on having substantial biomass. The southeastern region is capable of producing cover crop biomass in excess of 9000 kg ha(-1), which is sufficient for weed control in many cash crops, although supplementary weed control is sometimes necessary. Long-term data are needed to predict when farmers should add supplementary weed control. More work is also needed on how much additional N is required for the cash crops and how best to deliver that N in a high-residue environment using organic sources.
  • Authors:
    • Nyakatawa, E. Z.
    • Reddy, S. S.
    • Reddy, C. K.
  • Source: International Journal of Agriculture & Biology
  • Volume: 14
  • Issue: 1
  • Year: 2012
  • Summary: Nitrogen uptake pattern by cotton (Gossypium hirsutum L.) at different growth stages in response to long-term application of poultry litter (PL) in a no-till system (NT) was studied on a silt loam soil in 2009. The study was done in plots that were established in 1996 at TVREC, Belle Mina, AL, USA. Treatments included were three tillage [conventional tillage (CT), mulch-tillage (MT), and no-tillage (NT)] two cropping systems tot ton-lye (C-R; cotton in summer & cereal rye cover crop in winter), and cotton-fallow (C-F; cotton in summer & fallow in winter)] and two sources of nitrogen [PL at 100 and 200 kg N ha(-1) and ammonium nitrate (AN) at 100 kg N ha(-1)] Out of all treatment combinations only 11 important treatments were selected and arranged in a randomized complete block design and replicated 4 times. Results in 2009, showed that NT system can supply equal quantity of nitrogen compared to CT at all growth stages. No-tillage recorded similar growth, yield and total nitrogen uptake compared to CT. Application of PL at 100 kg N ha(-1) showed significantly superior plant growth compared to AN at early growth stage, but the differences disappeared as the plant growth progressed. Similar yields and nitrogen uptake were observed with application of either PL or AN at 100 kg N ha(-1). Application of a double rate of PL (200 kg N ha(-1)) resulted in significantly higher nitrogen uptake compared to that of PL or AN at 100 kg N ha(-1), but a significant yield advantage was not observed with this higher rate. Of the total nitrogen extracted by cotton at maturity, 50% uptake was completed by early flowering stage and 97% was completed by boll development stage. At maturity, the majority of nitrogen (52%) was partitioned into seeds, while the rest was distributed into leaves (16%), stems (18%) and reproductive parts (14%). winter rye cover crop did not influence nitrogen uptake. (C) 2012 Friends Science Publishers