19832015
  • Authors:
    • Weeks, C.
    • Cordingley, N.
    • Flower, K. C.
    • Ward, P. R.
    • Micin, S. F.
  • Source: Field Crops Research
  • Volume: 132
  • Year: 2012
  • Summary: Modern conservation agriculture practices aim to maintain year-round ground cover in order to maximise soil protection from extremes of temperature and minimise erosion risk. However, in Mediterranean-style environments with hot dry summer periods, maintaining ground cover can be difficult, as these periods are generally too arid for plant growth. In this research, we investigated the use of cover crops, grown solely to increase ground cover and not harvested for grain or biomass, in a Mediterranean climate. Specifically, we examined the impact of cover crops and residue retention on evapotranspiration, both over the summer fallow period and during the winter and spring crop growth period, and on deep drainage from subsequent crops, on two contrasting soil types in south-western Australia. The impact of cover crops on weed populations and nitrogen dynamics is described in a companion paper. In contrast to previously published research, cover crops and residue retention were found to have limited impact on total evaporation during the summer and autumn period, although there were occasional short-term impacts on the rate of evaporation shortly after rainfall. There was also limited evidence of changes in evaporation during early crop growth. Drainage from crops grown after cover crops was not consistently different to drainage from crops grown after conventional crops. The inclusion of cover crops in farming systems in regions with a Mediterranean climate is unlikely to have major impacts on the water balance, but may still increase overall sustainability of the farming system.
  • Authors:
    • Guimaraes, R. M. L.
    • Tormena, C. A.
    • Blainski, E.
    • Nanni, M. R.
  • Source: REVISTA BRASILEIRA DE CIENCIA DO SOLO
  • Volume: 36
  • Issue: 1
  • Year: 2012
  • Summary: Soil management strategies to improve and maintain soil physical quality (SPhQ) are essential for the sustainability of intensive agricultural systems. The least limiting water range (LLWR) is an indicator of SPhQ defined by the range of least restrictive soil water content to plants, i.e., a soil water content within the LLWR indicates an appropriate SPhQ for plants. In this context, soil mulching with crop residues can contribute to the SPhQ by increasing the frequency at which soil water availability is maintained within the LLWR (F within). The purpose of this study was to determine the LLWR of an Oxisol under no-tillage soybean and to evaluate F within under application of oat residue (0; 3; 6; 9; and 12 Mg ha -1) to the soil surface. An inverse relation of the LLWR with soil bulk density (Bd) was observed. With decreasing LLWR, F within decreased, independently of the oat residue rate. However, an increase in residue application increased the F within values, independent of the sampling position. The beneficial effect of the increase of residue amount on F within depended on the amplitude of the LLWR. With the increase of Bd and reduction of LLWR, higher residue amounts on the soil did not result in an increase of F within or of SPhQ, mainly when Db was close to the critical soil bulk density.
  • Authors:
    • Khan, M.
    • Said, G.
    • Khan, M.
    • Khan, S.
    • Inayat, U.
    • Khalid, U.
  • Source: Journal of Integrative Agriculture
  • Volume: 11
  • Issue: 6
  • Year: 2012
  • Summary: Conservational tillage (CT) in combination with broad spectrum herbicide may be more efficient and economical in controlling weeds, reducing cost of cultivation, and enhancing wheat yield. Field experiments were carried out to evaluate the effect of tillage and herbicides on weeds and wheat yield under rice-wheat cropping system (RWCS). The results indicated that broad spectrum herbicides particularly, carfentrazone ethyl ester+isoproturon (Affinity 50 WDG) reduced weeds density by 93 and 95% compared to control and also produced the maximum grain yield (6818 and 6996 kg ha -1) and HI (harvest index, 44.7 and 44.6%) in 2007-2008 and 2008-2009 growing seasons, respectively. The maximum weeds infestation and the lowest yield were recorded in control. Tillage methods significantly influenced grain yield and HI, while no significant effect on all other parameters. The overall mean yield was significantly higher in zero tillage (5575 kg ha -1) and reduced tillage (5584 kg ha -1) compared to CT (5479 kg ha -1). Besides increasing wheat yield, Affinity 50 WDG and zero tillage are important weed management practices that can be integrated into wheat production in RWCS. However, in case of perennial weeds or insect pests' infestation, CT in combination with Affinity 50 WDG would be more productive than conservation tillage.
  • Authors:
    • Chen, C.
    • Xu, Z.
    • Koetz, E.
    • Wu, H.
    • Zhou, X.
  • Source: Applied Soil Ecology
  • Volume: 53
  • Year: 2012
  • Summary: The conservation farming systems coupled with stubble retention are now widely adopted in southern Australia to improve soil fertility. However, little information is available about the effects of winter crops on soil labile organic carbon (C) and nitrogen (N) pools, especially in an arid agricultural ecosystem. In this study, eight winter cover crop treatments were used to investigate their effects on soil labile organic C and N pools and microbial metabolic profiles and diversity in temperate Australia. These treatments included two legume crops (capello woolly pod vetch and field pea), four non-legume crops (rye, wheat, Saia oat and Indian mustard), and a mixture of rye and capello woolly pod vetch as well as a nil-crop control. At the crop flowering stage, soil and crop samples were collected from the field and we examined aboveground crop biomass, soil NH 4+-N, NO 3--N, extractable organic C (EOC) and N (EON) concentrations using methods of 2 M KCl and hot water, microbial biomass, biologically active organic C (C Bio), and substrate-induced respiration (SIR) using the MicroResp method. Results showed that the crop treatments had lower soil moisture content, NO 3--N and the ratios of EOC to EON, but higher pH, NH 4+-N, EOC, EON, C Bio, microbial metabolic diversity index ( H) and evenness index compared with the control. There were no significant differences in microbial biomass C and N among the treatments. Although no pronounced differences in EOC and EON concentrations were found between the legumes and non-legumes, the legume treatments had lower SIR and higher H than the non-legume treatments. Principal component analysis showed that soil microbial metabolic profiles under the crops were different from those of the control, and the crop treatments had a clear separation along principal component 2. In addition, redundancy analysis showed that soil pH and moisture content were the most important influencing factors, along with EON and crop biomass, determining the patterns of microbial metabolic profiles under the crops.
  • Authors:
    • Villalobos, F.
    • Gomez-Macpherson, H.
    • Boulal, H.
  • Source: Field Crops Research
  • Volume: 130
  • Year: 2012
  • Summary: In the Mediterranean region, conservation agriculture principles like minimum soil disturbance or retaining residues on soil surface are rarely applied in irrigated annual cropping systems. This paper compares a conservation agriculture practice, permanent bed planting (PB), with a conventional system in which the ridges are reformed annually (CB). Comparisons were made throughout a crop sequence of cotton (Gossypium hirsutum L)-maize (Zea mays L) - cotton in which PB was introduced before the maize cropping. Traffic was controlled during the study. Both maize and cotton crops produced higher leaf area index and biomass under PB than CB and Sand 24% higher yield respectively though the yield benefit for maize was not significant. The PB system did not improve Water-use Efficiency but delayed water use until the later growth stages. Soil organic matter (SUM) was significantly higher in PB compared to CB one year after the introduction of the system, and this difference was due to higher SUM in the 0-0.05 m layer, particularly in the furrows. The lack of negative effects of PB on yield and the positive effects on SUM, coupled with increased water infiltration and reduced erosion shown in previous studies, point to the beneficial adoption of PB in the region assuming the patterns are confirmed in the longer term. (C) 2012 Elsevier B.V. All rights reserved.
  • Authors:
    • Diker, K.
    • Sezen, S.
    • Tekin, S.
    • Unlu, M.
    • Onder, S.
    • Kanber, R.
  • Source: Turkish Journal of Agriculture and Forestry
  • Volume: 36
  • Issue: 1
  • Year: 2012
  • Summary: In this study, the water saving and conservation potential of various furrow irrigation management techniques for irrigated cotton were compared. Conventional every-furrow irrigation with open-end furrows (EFO) and blocked-end furrows (EFB), and alternate every-other-furrow management with open-end furrows (AFO) and blocked-end furrows (AFB), were considered. Considerable seasonal water savings were obtained with AFO and AFB flows, on average from 717 mm to 906 mm, respectively, when compared to EFO. Alternate furrows showed the ability to reduce tailwater runoff considerably. When compared with EFO, water use was reduced by 9063 m(3) ha(-1) (60%) using AFB and 7167 m(3) ha(-1) (48%) using AFO, with decreases in yield of 765 kg ha(-1) (27%) and 492 kg ha(-1) (17%), respectively. Similarly, average water use efficiencies were 0.36 kg m(-3) for AFB and 0.31 kg m(-3) for AFO, compared to 0.20 kg m(-3) for EFO. Results showed the possibility of applying alternate-flow furrow management techniques for water conservation in cotton irrigation. Additionally, the alternate furrow method could also be considered as a deficit irrigation approach in the Harran Plain.
  • Authors:
    • Antle, J. M.
    • Ogle, S. M.
  • Source: Climatic Change
  • Volume: 111
  • Issue: 3/4
  • Year: 2012
  • Summary: Previous research has demonstrated that soil carbon sequestration through adoption of conservation tillage can be economically profitable depending on the value of a carbon offset in a greenhouse gas (GHG) emissions market. However adoption of conservation tillage also influences two other potentially important factors, changes in soil N2O emissions and CO2 emissions attributed to changes in fuel use. In this article we evaluate the supply of GHG offsets associated with conservation tillage adoption for corn-soy-hay and wheat-pasture systems of the central United States, taking into account not only the amount of carbon sequestration but also the changes in soil N2O emission and CO2 emissions from fuel use in tillage operations. The changes in N2O emissions are derived from a meta-analysis of published studies, and changes in fuel use are based on USDA data. These are used to estimate changes in global warming potential (GWP) associated with adoption of no-till practices, and the changes in GWP are then used in an economic analysis of the potential supply of GHG offsets from the region. Simulation results demonstrate that taking N2O emissions into account could result in substantial underestimation of the potential for GHG mitigation in the central U.S. wheat pasture systems, and large over-estimation in the corn-soy-hay systems. Fuel use also has quantitatively important effects, although generally smaller than N2O. These findings suggest that it is important to incorporate these two effects in estimates of GHG offset potential from agricultural lands, as well as in the design of GHG offset contracts for more complete accounting of the effect that no-till adoption will have on greenhouse gas emissions.
  • Authors:
    • Carr, P. M.
    • Anderson, R. L.
    • Lawley, Y. E.
    • Miller, P. R.
    • Zwinger, S. F.
  • Source: Renewable Agriculture and Food Systems
  • Volume: 27
  • Issue: Special Issue 01
  • Year: 2012
  • Summary: The use of killed cover crop mulch for weed suppression, soil erosion prevention and many other soil and crop benefits has been demonstrated in organic no-till or zero-till farming systems in eastern US regions and in Canada. Implements have been developed to make this system possible by terminating cover crops mechanically with little, if any, soil disturbance. Ongoing research in the US northern Great Plains is being conducted to identify cover crop species and termination methods for use in organic zero-till (OZ) systems that are adapted to the crop rotations and climate of this semi-arid region. Current termination strategies must be improved so that cover crop species are killed consistently and early enough in the growing season so that subsequent cash crops can be grown and harvested successfully. Delaying termination until advanced growth stages improves killing efficacy of cover crops and may provide weed-suppressive mulch for the remainder of the growing season, allowing no-till spring seeding of cash crops during the next growing season. Excessive water use by cover crops, inability of legume cover crops to supply adequate amounts of N for subsequent cash crops and failure of cover crops to suppress perennial weeds are additional obstacles that must be overcome before the use of killed cover crop mulch can be promoted as a weed control alternative to tillage in the US northern Great Plains. Use of vegetative mulch produced by killed cover crops will not be a panacea for the weed control challenges faced by organic growers, but rather one tool along with crop rotation, novel grazing strategies, the judicious use of high-residue cultivation equipment, such as the blade plow, and the use of approved herbicides with systemic activity in some instances, to provide organic farmers with new opportunities to incorporate OZ practices into their cropping systems. Emerging crop rotation designs for organic no-till systems may provide for more efficient use of nutrient and water resources, opportunities for livestock grazing before, during or after cash crop phases and improved integrated weed management strategies on organic farms.
  • Authors:
    • Djigal, D.
    • Saj, S.
    • Rabary, B.
    • Blanchart, E.
    • Villenave, C.
  • Source: Soil & Tillage Research
  • Volume: 118
  • Year: 2012
  • Summary: Conservation agriculture (CA) is rapidly developing in Madagascar but little is known about its effects on local soil functioning. To assess some of those effects, we investigated the effects of three CA systems and two levels of fertilization on soil functioning using nematofauna as indicator. The systems consisted in (i) soybean (Glycine max L.)-maize (Zea mays L) rotation with mulch of residues, CA-R; (ii) bean (Phaseolus vulgaris L.)-soybean rotation with living mulch of Pennisetum clandestinum, CA-K; (iii) continuous maize with living mulch of Desmodium uncinatum, CA-D and were compared with soybean-maize under conventional tillage (CT) and natural fallow (NF). The fertilization levels consisted in ( i) farmyard manure, FYM; and (ii) farmyard manure + mineral fertilizers, FYM + NPK. Located in the Highlands of Madagascar, the experiment was setup in 1991 and andic Dystrustept soil had been sampled in 2005-2007. We measured nematode abundances and ecological indices as well as the abundance and biomass of soil macrofauna, soil water and organic C and N contents and plant yields. We hypothesized that (1) CA including maize in monoculture would lead to higher abundance of plant-parasitic nematodes; (2) both dead-residue mulch and inorganic fertilization would lead to a more basal nematode community structure; and (3) that the combination of system effects on soil nematode community would be able to forecast differential crop yields for the CA systems. Our results show that CA systems tested were able to support better/comparable maize and soybean yields compared with CT, provided that crop rotation is correctly managed. Supporting our first hypothesis, abundance of plant parasitic nematodes was (40-150 times) higher under maize monoculture. Abundance of soil nematofauna and trophic groups (excepted carnivores and omnivores) was stable during the three years. Inorganic fertilization increases carnivorous and omnivorous nematodes to 122% and 140%, respectively. Ecological indices showed that soil functioning of CA systems was intermediate between that NF and CT. CA systems were characterized by a highly structured soil food-web compared with CT. Yet, soil processes intensity revealed to be lower in CA with dead mulch compared with CA with living mulch, contrasting with our second hypothesis. The characterization of nematofauna discriminated well the different systems and supports our third hypothesis. Nematode structure and enrichment indices were significantly correlated to soil organic C and N content as well as grain yields. They proved to be powerful bio-indicators of soil functioning in the CA systems studied.
  • Authors:
    • Duke, J. M.
    • Borchers, A. M.
    • Johnston, R. J.
    • Absetz, S.
  • Source: Ecological Economics
  • Volume: 74
  • Year: 2012
  • Summary: This paper describes the results of a choice experiment measuring social benefits for sustainable management practices and agricultural land preservation. Sustainable management is conceptualized with three illustrative practices that impact water quality, carbon sequestration, and soil erosion: fertilizing with a broiler litter product, expanding riparian buffers, and no-till cropping. Data for a choice experiment are collected using a mail survey of residents living near a large, unpreserved agricultural parcel in an urban-influenced area of Delaware. Results identify substantial benefits for land preservation, the use of broiler litter, and riparian buffers but not for conservation tillage. Results also suggest that the estimated household benefits of all three sustainable management practices combined are similar in magnitude to the benefits from land preservation alone. Based on model results, policy and future research may wish to examine possibilities for subsidizing sustainable management practices in urban-influenced areas as a more cost-effective means of providing benefits similar to those realized through land preservation.