• Authors:
    • Bates, R. T.
    • Gallagher, R. S.
    • Curran, W. S.
    • Harper, J. K.
  • Source: Agronomy Journal
  • Volume: 104
  • Issue: 2
  • Year: 2012
  • Summary: Conservation tillage for corn (Zea mays L.) production has greatly reduced the soil erosion potential in these systems, but relies heavily on herbicides to manage weeds. Overreliance on herbicides can lead to the development of herbicide-resistant weed communities and increase the risk of ground and surface water contamination by residual herbicides. This study evaluates the integration of various mechanical soil/weed management implements and herbicide programs for surface residue cover, weed control, corn productivity, and economic net returns. A pre-plant vertical coulter/rotary harrow tended to control small annual weeds as well as a standard burn down herbicide program, but reduced surface residue cover by 15% compared to the no-till check treatments. The high residue rotary hoe had little effect on surface residue cover, but provided inconsistent early-season weed control. The high residue inter-row cultivator resulted in 23% residue cover compared to 50% in the no-till treatments, but reduced weed biomass by 53% without any supplemental residual herbicides and 88% with a banded residual herbicide compared to the weedy check treatment. Crop productivity and net return data suggest that integrating the vertical coulter/rotary harrow, high residue cultivator, and banded residual herbicide program could reduce herbicide ai rates by 70% and still achieve similar corn yields and economic returns as the herbicide intensive systems. Such integrated mechanical-chemical systems will increase the crop management complexity for farmers, which may hinder adoption. Soil erosion potential of the integrated systems requires further in-depth evaluation.
  • Authors:
    • Bejiga, G.
    • Khalil, Y.
    • Kumar, S.
    • Haddad, A.
    • Piggin, C.
    • Ahmed, S.
  • Source: Soil & Tillage Research
  • Volume: 121
  • Year: 2012
  • Summary: Conservation agriculture is becoming popular due to its potential for enhanced productivity and cost savings among small scale farmers in developing countries. The International Center for Agricultural Research in Dry Areas is promoting conservation cropping systems that involve cereal-legume rotation in West Asia and North Africa region. Studies were made on the impact of long-term rotation trial on diseases of chickpea and lentil as well as the evaluations of lentil genotypes for their reactions to Fusarium wilt and downy mildew under two tillage practices. In the long-term rotation trials, the two season results showed no significant differences between tillage practices, crops and planting dates and their interactions in affecting mean percent cyst nematode disease. The mean cyst nematode disease incidence ranged from 7.3% on early planted lentil on CT to 14.5% in late planted chickpea on ZT. Tillage practices significantly ( P≤0.05) affected Ascochyta blight incidence but not its severity. The incidence ranged from 4% to 22.5% under early planted chickpea on both tillage practices. Moreover, the mean severity ranged from 3.2 to 5.5 rating in early planted CT and ZT, respectively. The combined analysis showed significant differences ( P≤0.05) among genotypes but not their interactions with tillage for Fusarium wilt and downy mildew reactions. All the genotypes showed less than 10% Fusarium wilt mortality indicating high levels of resistance. The mean downy mildew severity ranged from 1.3 in ILL-7991 to 2.6 rating in ILL6994. This study showed that both soil borne and foliar diseases could be a problem in conservation cropping system and continuous monitoring of diseases is essential to prioritize management practices in relation to conservation agriculture in Mediterranean type environments. Moreover, cool-season legume genotypes with disease resistance and high yield can be developed under conservation agriculture that could also serve traditionally tilled production systems.
  • Authors:
    • Bergheaud, V.
    • Benoit, P.
    • Alletto, L.
    • Coquet, Y.
  • Source: Pest Management Science
  • Volume: 68
  • Issue: 4
  • Year: 2012
  • Summary: BACKGROUND: Sorption largely controls pesticide fate in soils because it influences its availability for biodegradation or transport in the soil water. In this study, variability of sorption and desorption of isoxaflutole (IFT) and its active metabolite diketonitrile (DKN) was investigated under conventional and conservation tillage. RESULTS: According to soil samples, IFT KD values ranged from 1.4 to 3.2 L kg -1 and DKN KD values ranged from 0.02 to 0.17 L kg -1. Positive correlations were found between organic carbon content and IFT and DKN sorption. IFT and DKN sorption was higher under conservation than under conventional tillage owing to higher organic carbon content. Under conservation tillage, measurements on maize and oat residues collected from the soil surface showed a greater sorption of IFT on plant residues than on soil samples, with the highest sorbed quantities measured on maize residues ( KD ~45 L kg -1). Desorption of IFT was hysteretic, and, after five consecutive desorptions, between 72 and 89% of the sorbed IFT was desorbed from soil samples. For maize residues, desorption was weak (
  • Authors:
    • Schlegel, A.
    • Halvorson, A.
  • Source: Agronomy Journal
  • Volume: 104
  • Issue: 5
  • Year: 2012
  • Summary: Limited irrigation management practices are being used in the Central Great Plains to conserve water by optimizing crop water use efficiency. Limited irrigation may reduce total crop biomass production and amount of crop residue returned to the soil. Crop residue production within four no-till (NT) crop rotations [continuous corn ( Zea mays L.) (CC); corn-winter wheat ( Triticum aestivum L.) (CW); corn-winter wheat-grain sorghum ( Sorghum bicolor L. Moench) (CWS); corn-winter wheat-grain sorghum-soybean [ Glycine max (L.) Merr.] (CWSSb)] was measured and changes in soil organic carbon (SOC) and total soil nitrogen (TSN) stocks were monitored for 10 yr. Crop residue yields varied with crop being produced and with rotation, as did residue N and C returned to the soil. The C/N ratio of the residue varied with crop. The SOC and TSN pools increased with time in all rotations. The rate of gain in SOC and TSN mass for each rotation was 717, 477, 335, and 270 kg SOC ha -1 yr -1 and 114, 92, 87, and 84 kg TSN ha -1 yr -1 for the CC, CW, CWS, and CWSSb rotations, respectively, in the 0- to 30.5-cm soil depth. The rate of change in SOC and TSN mass was lowest with CWSSb (8.7 Mg residue ha -1 yr -1) and highest with CC (12.0 Mg residue ha -1 yr -1). Approximately 6.8 to 7.6 Mg residue ha -1 yr -1 would be needed to maintain SOC stocks under limited irrigation.
  • Authors:
    • Limon, M.
    • Blanco-Moure, N.
    • Lopez, M.
    • Gracia, R.
  • Source: Soil & Tillage Research
  • Volume: 118
  • Year: 2012
  • Summary: Conservation tillage has been encouraged as a management alternative to preserve soil and water resources in semiarid Aragon (NE Spain). In fact, its adoption by farmers, and especially of no tillage (NT) systems, has increased in recent years. However, little information concerning the soils on which these techniques are applied is available for this region. The objective of this study was to assess the potential of NT to increase organic carbon content at the soil surface (0-20 cm) in rainfed Aragon. To this aim, 22 pairs of adjacent farm fields under NT and conventional tillage (CT) were compared in different cereal production areas. The fields were under continuous NT between 5 and 19 years but half were over 10 years. Soil organic carbon (SOC) in NT ranged from 7.06 to 18.53 g kg -1 (0-20 cm depth) and was higher than 12 g kg -1 in nearly 30% of the fields. These contents represented between 8% less (only one case) and 55% more SOC under NT than under CT with an average gain of 20% in favour of NT. The highest SOC contents were found in the NT fields of longer duration (>10 years) and/or managed with practices that enhance the return of more crop biomass to the soil (complete residue return, cropping intensification and manure application). The identification of the current management practices used by farmers has allowed us to know the diversity of the NT-based cropping systems and the reality of the conservation agriculture in our region. Overall, results from this on-farm study indicate that NT can be recommended as a viable alternative to CT to increase organic carbon at the soil surface in cereal production areas of Aragon.
  • Authors:
    • van Ranst, E.
    • Fadlaoui, A.
    • Moussadek, R.
    • Mrabet, R.
  • Source: Field Crops Research
  • Volume: 132
  • Year: 2012
  • Summary: Moroccan agriculture is characterized by the co-existence of both modern and smallholder traditional agriculture. Both types of agriculture are under degradative processes due to mis-use of tillage implements, mis-management of crop residues and inappropriate links between grain and livestock productions. From the research conducted over the last three decades, the vast majority of beneficial tillage effects are transient. Conversely, the harmful effects of conventional tillage (CT) systems are long-lasting, if not permanent. The present paper aims at evaluating major achievements in conservation or no-tillage agriculture (CA or NT) research conducted in dry areas of Morocco and presenting important ways to implement these achievements within the Moroccan rural society. CA has been introduced in response to issues of soil conservation, drought mitigation and soil quality management. NT systems have resulted in reduced soil erosion, greater soil water conservation, improved soil quality and stable and higher crop yields. Changes in crop production practices due to shifting to NT or CA systems and retention of crop residues at or near the surface produced progressive qualitative and quantitative variations in soil organic matter. This can allow agriculture to contribute to country's efforts to reduce and control greenhouse gas emissions. These effects benefited both farmers and society in terms of higher returns and efficiencies. Under NT, benefits from improved agriculture's environmental performance must be added to remunerations of reducing costs of production and improving well-being of farmers. The other strong benefits that CA brings come from the opportunity for early sowing and savings in time, machinery and fuel. Even though, many agronomic, socio-economic and environmental benefits accrue from NT and increasing crop diversity; lack of incentives from the government and social factors encourage the continued use of CT systems. CA systems were sufficiently tested in research stations but found limited adoption in farm communities. The shift in the late nineties to more on-farm research did not result in the envisaged breakthroughs, mainly due to poor research-extension linkages and several social and technical barriers. Consequently, in order to realize durable agricultural growth, there is a huge challenge to out- and up-scale CA in Morocco through linkage of all stakeholders (farmers, developers, researchers, industrials and policy makers). This paper fulfills information gaps and presents a thorough discussion on constraints to CA adoption as well. (C) 2011 Elsevier B.V. All rights reserved.
  • Authors:
    • Torbert, H.
    • Watts, D.
    • Way, T.
    • Mays, D.
    • Nyakatawa, E.
    • Smith, D.
  • Source: Journal of Sustainable Agriculture
  • Volume: 36
  • Issue: 8
  • Year: 2012
  • Summary: Soil management practices can alter the natural balance at the soil-plant-atmosphere ecosystem interface, which can significantly affect the environment. This study compared CO2 fluxes in conventional tillage (CT) and no-tillage (NT) corn (Zea mays L.) production systems receiving poultry litter (PL) and ammonium nitrate (AN) fertilizers on a Decatur silt loam soil in the Tennessee Valley region of North Alabama from Spring 2008 to Fall 2009. Soil CO2 flux in CT plots (9.5 kg CO2 ha(-1) day(-1)) was significantly greater than that in NT plots (4.9 kg CO2 ha(-1) day(-1) in summer. Soil CO2 fluxes were lowest in fall where CT plots had a mean soil CO2 emission of 0.8 kg CO2 ha(-1) day(-1), while plots under NT and grass fallow system were sinks of CO2 with fluxes -0.6 and -1.0 kg CO2 ha(-1) day(-1), respectively. Mean soil CO2 flux averaged over seasons in NT plots was 36% lower than that in CT plots. Grass fallow plots were net sinks of CO2 with a mean CO2 flux of -0.4 kg CO2 ha(-1) day(-1). Our study showed that application of PL or AN fertilizer in NT systems can significantly reduce soil CO2 emissions compared to CT systems in corn production.
  • Authors:
    • Coleman, K.
    • Dailey, A. G.
    • Glendining, M. J.
    • Goulding, K. W. T.
    • Whitmore, A. P.
    • Powlson, D. S.
  • Source: Sustainability
  • Volume: 4
  • Issue: 10
  • Year: 2012
  • Summary: Given that we must farm land in order to eat, the total environmental burden imposed by farming a crop, such as winter wheat in the UK, appears to be close to the minimum given current production techniques. The value of the services other than food production, such as flood water buffering, pollination, carbon storage and so on, that land can provide is relatively large compared with the value in reducing environmental burdens from pesticide use, nutrient pollution and greenhouse gas emissions that might arise by farming less intensively. More land will need to be brought into cultivation in order to provide the same amount of food if the intensity of farming is reduced and the resultant loss of ecosystem services (ES) outweighs the reduction in other burdens. Nevertheless, losses of nutrients, especially nitrogen (N), from agriculture are a serious concern and the current cost of the environmental footprint of agriculture is significant compared with the value of the food it produces. This article examines nutrient burdens and analyses the means by which the total environmental burden might be reduced relative to productivity. These include increasing the efficiency of farming, removing constraints to yield, and establishing multiple uses for land at the same time as farming. It concludes that agronomic measures which improve nutrient capture and which obtain more yield per unit area are valuable means to avoid degradation of environmental quality because both nutrient pollution and land consumption can be avoided.
  • Authors:
    • Okeyo, J.
    • Vanlauwe, B.
    • Kimetu, J. M.
    • Waswa, B.
    • Bationo, A.
    • Kihara, J.
    • Mukalama, J.
    • Martius, C.
  • Source: Experimental Agriculture
  • Volume: 48
  • Issue: 2
  • Year: 2012
  • Summary: Reduced tillage is said to be one of the potential ways to reverse land degradation and ultimately increase the productivity of degrading soils of Africa. We hypothesised that crop yield following a modest application of 2 t ha(-1) of crop residue in a reduced tillage system is similar to the yield obtained from a conventional tillage system, and that incorporation of legumes in a cropping system leads to greater economic benefits as opposed to a cropping system involving continuous maize. Three cropping systems (continuous maize monocropping, legume/maize intercropping and rotation) under different tillage and residue management systems were tested in sub-humid western Kenya over 10 seasons. While soybean performed equally well in both tillage systems throughout, maize yield was lower in reduced than conventional tillage during the first five seasons but no significant differences were observed after season 6. Likewise, with crop residue application, yields in conventional and reduced tillage systems are comparable after season 6. Nitrogen and phosphorus increased yield by up to 100% compared with control. Gross margins were not significantly different among the cropping systems being only 6 to 39% more in the legume-cereal systems relative to similar treatments in continuous cereal monocropping system. After 10 seasons of reduced tillage production, the economic benefits for our cropping systems are still not attractive for a switch from the conventional to reduced tillage.
  • Authors:
    • Tivet, F.
    • Khamxaykhay, C.
    • Rattanatray, B.
    • Jullien, F.
    • Quoc, H. T.
    • Lestrelin, G.
  • Source: Renewable Agriculture and Food Systems
  • Volume: 27
  • Issue: 1
  • Year: 2012
  • Summary: Over the past half-century, major efforts have been made worldwide to develop sustainable alternatives to agricultural tillage. In line with these efforts, two main research development initiatives have supported the experimentation and dissemination of conservation agriculture (CA) in Laos. Here we present the results of a 4-year monitoring and evaluation study conducted in 21 villages targeted for dissemination. In a context of rapid transition to intensive commercial agriculture in Laos, CA has become an important constituent of agricultural landscapes. However, there are significant variations in adoption rates across the study region. Statistical and qualitative evidence suggests that experimentation and adoption are not contingent upon farm-level variables such as capital, labor, age and education. While access to land helps shape local decision-making, the land tenure threshold under which farmers are not willing to experiment with alternative cropping systems is relatively low and highly variable in both space and time. Rather, experience and awareness of land degradation, production costs, social cohesion and leadership appear to be key factors in explaining most variations in local adoption rates. These results indicate that the practice of CA is not necessarily incompatible with smallholder farming. However, while complex crop associations and rotations are necessary for integrated weed control and reduced chemical use, their diffusion would require a broader transformation of the agricultural industry and the current market demand.