Browsing by Subject "Soil conservation"

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An economic analysis of the implementation options of soil conservation policies
(2008) Schuler, Johannes; Dabbert, Stephan
The objective of this study is to analyze the economic and agricultural aspects of the implementation of soil conservation programmes and to suggest appropriate measure-instrument combinations for efficient soil conservation as a decision support for the implementation of soil conservation policies. Emphasis is given to the resource and institutional economics of soil conservation. In the empirical part, the efficiency of policy options is analysed using the example of a region in north-eastern Germany based on model calculations. After an introduction to the topic of soil functions and soil degradation definitions, the implementation concepts for soil protection measures at the international and national level are described. Based on the theoretical economic analysis of soils as a natural resource, the existing property rights, the public good characteristics of soils and the resulting externalities lead to the conclusion that market failure does exist. Therefore, the non-market coordination of soil use is justified. A cost-effectiveness analysis was derived based on the theory of ?safe-minimum-standard? for the appropriate assessment of the implementation options of soil conservation policies. A fuzzy-logic-based method, which is based on an expanded Universal Soil Loss Equation approach (USLE), was applied for the assessment of soil erosion risk in the sample region. The approach considers both the natural conditions and the characteristics of the cropping practice. The very detailed description of the cropping practices allowed for the specific assessment of erosion relevant effects. This, in combination with the high detail site descriptions provided this study with a very precise regional approach. The regional decision-support system MODAM (multi-objective decision support tool for agro-ecosystem management) was applied for the assessment of the economic and environmental impacts of different policy options. The policy scenarios examined include a CAP reform scenario with decoupled payments in accordance with the proposed conditions of the year 2013. This scenario was used as the reference scenario for the other possible scenarios of soil conservation policies. The three main scenarios for the policy options are 1) a non-spatially oriented, 2) a spatially-oriented incentive programmes for reduced tillage practices and 3) a regulation scenario that prohibits the cultivation of highly erosive crops (row crops) on erodible soils. The prohibition of row crops on highly erodible soils led both to lower on-farm costs and lower budget costs in comparison to the incentive programmes for reduced tillage. All three scenarios had comparable reduction in soil erosion. Based on the modeling results the ban on row crops on highly erodible sites is therefore the preferable option in terms of the cost-effectiveness ratio. The inclusion of transaction costs in this study helps expand the scope of policy analysis, for the total costs of a policy would be underestimated if only the budget costs for the direct payments to farmers were considered. Transaction costs understood as a cost for the (re-) definition and implementation of property rights can reach substantial amounts and reduce the total efficiency of a policy. The results of the qualitative analysis of the transaction costs of the study policy options also supported the option of row crop regulation on highly erodible soils. A model that serves as decision support for both the economic and agricultural aspects of soil conservation had been successfully developed in this study. Different policy options were analysed for a cost-effective solution of soil conservation programmes. Based on the final discussion on the involved transaction costs, the regulatory approach (a spatially-focussed ban on row crops) was shown to be the most cost-effective option with potentially lower transaction costs. The main criteria for a cost-effective policy design are high efficiency in both the agricultural measures (practices) and the spatial correlation between the programme area and the high erosion risk areas. Incentive programmes in combination with less effective agricultural practices showed a worse cost-benefit ratio for the sample area than the regulation approach, which is based on more effective agricultural practices.
Land Preparation Methods and Soil Quality of a Vertisol Area in the Central Highlands of Ethiopia
(2005) Jijo, Teklu Erkossa; Stahr, Karl
The industrialization of agriculture led to societal concerns for environmental protection and food quality in developed countries. On the other hand, the need for increased agricultural productivity to address the persistent poverty and food insecurity in developing countries is intensified. Thus, improved management systems to meet the double objectives of increased productivity and sustained environmental quality are increasingly required. The assessment of soil quality and productivity are among the means of monitoring the various management systems to achieve the goals. Among the interrelated definitions formulated for soil quality, a committee established by Soil Science Society of America for the same purpose defined it as the capacity of soil to function within natural and managed ecosystem boundaries to sustain plant and animal productivity, maintain or enhance soil, water and air quality and support human health and habitation. The central idea in most of the definitions is the capacity of the soil to function. The capacity of a soil to function depends on its inherent properties derived from its genesis and the dynamic properties resulting from the prevailing management systems. Most of the hitherto soil quality assessments considered agricultural production as the major management goal. As this study was conducted in the highlands of Ethiopia where food security remains a basic challenge, the primary management goal could not be different. Shortage and fragmentation of land driven by population pressure have become issues of concern in the area. With a continually dwindling national land-holding average of only one ha per household, farmers struggle to produce enough to feed their families. Since the possibility of expanding agricultural land is limited, increased production is realistic only from higher productivity per unit land per unit time. Covering about 8 million ha, Vertisols are among the high potential soils, where significant increase in productivity is likely. However, their productivity is constrained by their physical and hydrological properties, manifested by their hardness when dry and their stickiness when wet, impeding land preparation. The traditional management systems led neither to increased productivity nor to enhanced soil quality. Thus, the need for alternative technologies is paramount. Despite a concerted effort during the last two decades to develop improved technologies for the soils, land preparation for agricultural productivity and sustaiability remains a major challenge. In addition to technical difficulties associated with their nature and deep-rooted poverty and illiteracy, lack of farmers? participation is believed to have hampered the development and adoption of robust technologies. The challenge facing the soil management research in Ethiopia is thus double fold: development of technologies that swiftly increase agricultural production and ensure judicious use of the land resources. Farmers are the ultimate decision makers on their plots, at least in Ethiopia, often irrespective of the consequences of their decisions. Simple technologies are required to manipulate their decisions in favour of the desired goals. This requires development of technologies that fit into their aspiration, tradition and socio-cultural values with their participation in the generation and evaluation of the technologies. This study was to identify alternative land preparation methods for increased productivity and economic profitability, while maintaining or enhancing the soil quality of the Vertisols. The hypothesis tested was that the alternative land preparation methods improve soil productivity and maintain or enhance soil quality. Three alternatives, Broad Bed and Furrow (BBF), Green Manure (GM) and Reduced Tillage (RT) with the traditional method, Ridge and Furrow (RF) were compared for 6 years, setting crop yield, economic profitability, and soil erosion and soil quality as performance indicators. This on station experiment was complemented by a participatory assessment at a small watershed scale. The objectives of the latter were identification of local soil functions, definition of soil quality concepts, and identification of soil quality indicators and evaluation of the soils for the major functions. Land preparation methods influence soil functions through their effects on soils qualities. Among the soil physical quality indicators considered, GM increased aggregate stability and reduced surface crust strength due to its increased OM content and microbial activities. While RT led to least penetration resistance, infiltration, water-holding capacity, and moisture content were less sensitive to the treatments. The chemical characteristics and plant nutrients response was not consistent indicating the need of longer time for the effects to show a clear trend. Organic carbon and MBC content of the soil increased due to RT and GM, but the increment was not proportional leading to lower microbial quotient. This indicates SOM build up with a long-term soil quality improvement. The effect on runoff was inconsistent during the first three years (1998-2000), but BBF and RT slightly increased. In 2001 and 2002, BBF drained 67% and 54 %, respectively, of the seasonal rainfall as runoff while RT routed 61% and 53%. There is a non significant tendency of increased soil and nutrient losses from BBF and RT due to the increased runoff. BBF significantly increased the grain yield of lentils by 59% (1.03 t ha-1 to 1.63 t ha-1) compared to the control. Similarly, RT resulted in the highest grain yield of wheat (1.86 t ha-1) and tef (1.34 t ha-1). Economically, BBF is the most profitable option for lentils with 65% increase in total gross margin while RT resulted in 11% and 8% increase in gross margin of wheat and tef, respectively, as compared to the control. The soil quality index was not significantly affected by the land preparation methods. Nevertheless, GM has shown a slight enhancement with the highest SQI, followed by BBF and RT. Thus, the land preparation methods are favoured in order of GM> BBF> RT> RF, for soil quality. The relative enhancement of soil quality by GM was linked mainly to its increased Corg content. The performance indicators (productivity, economic profitability, soil conservation and soil quality) are also affected differently. A matrix ranking of the effects on the indicators showed that none of treatments is superior for all the indicators. The average of the ranks (no weight attached) showed that BBF was the most favourable followed by RT. Therefore, the methods are preferred in the order of BBF> RT>GM=RF considering the overall indicators. The superiority of BBF and RT corresponds to their productivity and economic benefits. For soil quality and erosion control, GM is a favourable option. However, as its economic benefit was low, further improvement is required. In addition, lack of fast growing legumes tolerant to both shortage and excess water, failure of the short rain for planting, cost of chopping and incorporating the cover crops and the possible need of special equipment for incorporating may hinder its wider application and hence need further investigation. The success of the alternatives depends on the farmers? capacity and willingness to invest. As the issues of soil quality and land degradation are more of societal concerns than of the individual farmers, external technical and financial incentives are desirable to enhance their capacity and to initiate their interest. Institutional and policy issues influencing agriculture and natural resource management and uncertainties like variation in weather deserve judicious consideration.
Soil conservation methods and their impact on nitrogen cycling and competition in maize cropping systems on steep slopes in Northwest Vietnam
(2015) Vu Dinh, Tuan; Cadisch, Georg
Recent maize cultivation expansion into steep forested uplands in Vietnam led to severe erosion, soil degradation, and strong environmental impacts. Despite effectively controlling erosion, conservation measures often reduce crop yields due to resource competition. To foster uptake of soil conservation, a study including two experiments with bounded plots at two communes - Chieng Hac (21.02° N, 104.37° E, inclination: 53%) and Chieng Khoi (21.02° N, 104.32° E, inclination: 59%) - was carried out over a period of three years (2009-2911). The treatments included maize monocropping under intensive tillage and fertilization (T1, control), maize with Panicum maximum as grass barrier (T2), maize under minimum tillage (MT) with Pinto peanut (Arachis pintoi) as cover crop (T3), and maize under MT and relay cropped with Adzuki beans (Phaseolus calcaratus) (T4). Soil loss in 2010 and 2011 were also measured using sediment fences on unbounded maize fields under current farmers’ practice. The first part of the study assessed the magnitude of erosion and the mitigation potentiality of soil conservation measures. Under farmers’ practice, annual soil losses of bounded plots reached up to 174 t ha-1, being much higher than those from unbounded fields (up to 111 t ha 1). The majority of the soil loss occurred early in the season, when high rainfall intensities coincided with a low percent ground cover (<30%). To keep erosion rates below a tolerable soil loss (3 t/ha/yr) on steep slopes (53-59%) under an average annual rainfall of 1270 mm, a theoretical minimum ground cover of 95% is required at the onset of the crop season which was hardly achievable under monoculture system. Under conservation measures erosion was reduced by 39-84% in grass barriers or by 93-100% in MT with cover crops. A yield decline of 26% was observed in grass barrier treatments or up to 35% of cover crop plots if Pinto peanuts were not cut on time. Both options provided animal feed, up to 5.5 t/ha/yr dry matter of grass or 1.8 t/ha/yr dry matter of Pinto peanuts. Despite these potential benefits, constraints such as labour for grass barriers and cover crop establishment and cutting it afterwards, or difficulties in accessing and collecting maize cobs due to proliferate growth of Adzuki beans may hinder adoption by local farmers. To increase the incentive for adoption, the conservation system also has to use N fertilizer more efficiently. Therefore, the second part of the study examined the fate of applied 15N-labelled urea at the Chieng Hac site in 2010. At harvest, 21.6% of the labelled 15N was recovered by maize in T1, 8.9% in T2, 29% in T3, and 30.9% in T4. In T2, maize and P. maximum competed heavily for N with a total of 23.6% of the applied 15N found in the barriers next to application point. About 46-73% of the maize N uptake was derived from the soil, showing the important role of inherent soil N in these fertilized systems. MT reduced 15N translocation to deeper soil layers (40-80 cm), indicating a safety net function. Downslope translocation (>17 m) of applied 15N was <0.1 kg ha-1 as the majority of 15N added was vertically translocated and intercepted by plants along the slope. Despite implementation of an improved fertilization method, approximately 24-46% of N-fertilizer was unaccounted for, presumably lost via volatilization, denitrification, and leaching below 80 cm. Measured data for plot level showed that current farming practice (T1) induced a negative N balance of -142 kg N ha-1 in which residue burning and erosion were major pathways for N losses. A less severe negative N balance in T2 was attributed to reduced N losses by erosion while positive N balances of MT treatments were accredited to strongly reduced N losses via erosion and abandonment of burning plant residues in these treatments. The third part of the study investigated causes of competition in conservation systems three years after their establishment (2011). A pre-test at Chieng Hac in 2010 showed that abundance of water and the lack of N fertilization induced low grain N concentrations, enriched 15N;13C values in leaves, and reduced maize grain yield. This pattern was also observed in maize rows grown next to grass barriers or in cover crop plots at Chieng Khoi under good water availability conditions, indicating that these yield declines were mainly forced by lack of N. Additionally, a positive water balance throughout the maize cropping season further confirmed that water stress was absent. Moreover, enriched 15N values of maize rows close to the barriers suggested that these plants had to rely on soil N rather than on 15N derived from fertilizer N. Similarly, results of MT with simultaneous growth of A. pintoi pointed to N competition, resulting in a maize yield decline due to vigorous cover crop growth in T3. In contrast, MT with a relay crop (T4) had a similar maize yield, leaf N concentration, d15N, d13C as the control, suggesting N and water competition did not occur. In conclusion, soil erosion and nitrogen balances of current farming practice showed the urgent need to safeguard land resources, counteracting soil degradation but maintaining crop yields. The tested conservation techniques provide a range of characteristics to be considered as a sustainable system. The grass barrier as well as conservation systems controlled erosion, while minimum tillage with a cover crop further improved the nitrogen balance, and finally minimum tillage with a relay crop adds another advantage in maintaining crop production. Likelihood of adoption, however, may vary with how well appropriate incentives and land use policy fit to the area.