Sustainable Agricultural Land Research Articles

Quantification and Implications of Soil Losses from Commercial Sod Production

Commercial sod farms occupy about 1.62 × 103 km2 of the landscape of the United States. Land managers generally consider sod farms on an equal footing with other, sustainable agricultural land uses. We measured soil losses associated with sod harvesting in farms in the northeastern United States. Sod harvest resulted in soil losses ranging from 74 to 114 Mg ha−1 yr−1, considerably higher than the tolerable soil loss of 6.7 Mg ha−1 yr−1 Soil losses were proportional to time under sod production, with soil removal rates of 0.833 cm yr−1 We estimate that sod harvesting in the United States results in the net, permanent loss of 12.0 to 18.7 Tg of agriculturally productive soil from sod farms—and associated ecosystem services—every year. The soil losses reported here have important implications in terms of land use planning, transactions involving the purchase of development rights, and tax deductions for

Evolution of Soil Structure and Fertility After Conversion of Native Sandy Desert Soil to Irrigated Cropland in Arid Region, China

Assessment of soil quality and its direction of change with time is a primary indicator of sustainable agricultural land management. In this study, the temporal changes in soil physical and chemical properties were determined after conversion of native desert soils to irrigated croplands in a marginal oasis of the arid region, northwest China. Soil samples were collected from seven closely located farm fields that had been cultivated for 3, 5, 10, 14, 23, 30, and 40 years after agricultural cultivation, from adjacent remnant uncultivated sandy land (0 year), and from farm fields in an old oasis cultivated for more than 50 years. All the soils in the study were Psamments that derived from the deposition of aeolian sand. After cultivation, significant changes in particle size distribution and aggregate size distribution and stability in the 0- to 20-cm surface soil only occurred in soils cultivated for more than 10 years, showing a consistently increasing pattern with increasing duration of cultivation. The result indicated that soil did not contain enough coarse aggregates to control wind erosion, suggesting the need to maintain residues on the soil surface to aid wind erosion control for these newly cultivated sandy soils. As cultivation time increased, soil organic carbon (SOC), total and available N and P, cation exchange capacity, and CaCO3 concentrations all increased. Soil organic carbon and total N concentrations increased by 6.4 times and 5.9 times, respectively, after 40 years of continuous cropping. The increased silt and clay content caused by irrigation with silt-laden river water plays an important role in the aggregate formation and SOC and nutrient accumulation and retention. The results also indicated that the evolution of desert soil toward the sustainable agricultural soil requires at least 50 years. The absolute amounts of soil aggregate, SOC, and nutrients are still low after 40 years of cropping and were insufficient to support sustaining crop production. Therefore, improved land management such as conservation tillage and crop and grass rotation is imperative to accelerate soil structure and fertility improvement and maintain long-term productivity of the farmlands.

A new method for assessing the sustainability of land-use systems (II): Evaluating impact indicators

In the past decade, numerous indicators and indicator sets for sustainable agriculture and sustainable land management have been proposed. In addition to their interest in comparing different management systems on an indicator by indicator basis, land managers are often interested in comparing individual indicators against a threshold, or, in order to study trade-offs, against each other. To this end it is necessary to (1) transform the original indicators into a comparable format, and (2) score these transformed indicators against a sustainability function. This paper introduces an evaluation method for land-use-related impact indicators, which was designed to accomplish these tasks. It is the second of a series of two papers, and as such it links into a larger framework for sustainability assessment of land use systems. The evaluation scheme introduced here comprises (1) a standardisation procedure, which aims at making different indicators comparable. In this procedure indicators are first normalised, by referencing them to the total impact they contribute towards, and then they are corrected by a factor describing the severity of this total impact in terms of exceeding a threshold. The procedure borrows conceptually from Life Cycle Assessment (LCA) Impact Analysis methodology; (2) a valuation procedure, which judges the individual standardised indicators with regard to sustainability. This methodology is then tested on an indicator set for the environmental impact of a spinach production system in Northwest Germany. The method highlights mineral resource consumption, greenhouse gas emission, eutrophication and impacts on soil quality as the most important environmental effects of the studied system. We then explore the effect of introducing weighting factors, reflecting the differing societal perception of diverse environmental issues. Two different sets of weighting factors are used. The influence of weighting is, however, small compared to that of the standardisation procedure introduced earlier. Finally, we explore the propagation of uncertainty (defined as a variable's 95% confidence limits) throughout the standardisation procedure using a stochastic simulation approach. The uncertainty of the analysed standardised indicator was higher than that of the non-standardised indicators by a factor of 2.0 to 2.5.

The Impact of Policy and Institutional Environment on Costs and Benefits of Sustainable Agricultural Land Uses: The Case of the Chittagong Hill Tracts, Bangladesh

As in other mountain regions of Asia, agricultural lands in the Chittagong Hill Tracts (CHT) of Bangladesh are undergoing degradation due primarily to environmentally incompatible land-use systems such as shifting cultivation (jhum) and annual cash crops. The suitable land-use systems such as agroforestry and timber tree plantation provide benefit to the society at large, but they might not provide attractive economic benefits to farmers, eventually constraining a wide-scale adoption of such land-use systems. Therefore, it is essential to evaluate agricultural land-use systems from both societal and private perspectives in the pursuit of promoting particularly environmentally sustainable systems. This article evaluated five major land-use systems being practiced in CHT, namely jhum, annual cash crops, horticulture, agroforestry, and timber plantation. The results of the financial analysis revealed the annual cash crops as the most attractive land use and jhum as the least attractive of the five land-use systems considered under the study. Horticulture, timber plantation, and agroforestry, considered to be suitable land-use systems particularly for mountainous areas, held the middle ground between these two systems. Annual cash crops provided the highest financial return at the cost of a very high rate of soil erosion. When the societal cost of soil erosion is considered, annual cash crops appear to be the most costly land-use system, followed by jhum and horticulture. Although financially less attractive compared to annual cash crops and horticulture, agroforestry and timber plantation are the socially most beneficial land-use systems. Findings of the alternative policy analyses indicate that there is a good prospect for making environmentally sustainable land-use systems, such as agroforestry and timber plantation, attractive for the farmers by eliminating existing legal and institutional barriers, combined with the provision of necessary support services and facilities.

Soil organic carbon as an indicator of environmental quality at the national scale: Inventory monitoring methods and policy relevance

Soil organic carbon (SOC) storage is an indicator of environmental quality for mineral soils because of the influence that organic matter has on key functional properties, such as fertility, soil structure and water relations. Historically, agricultural management has caused large losses of SOC relative to native ecosystems, leading to degradation. However, new technologies and conservation practices have been developed during the past few decades that can enhance SOC storage, and thus improve environmental quality. Our objective was to describe a national inventory procedure to estimate SOC storage for purposes of monitoring environmental quality. The major steps in this procedure include: (1) model selection/development, (2) model verification, (3) identification of model input data, (4) uncertainty assessment, (5) model implementation, and (6) validation of results. Applying this approach with a simple C accounting method, the upper 30 cm of US agricultural soils were estimated to have accumulated 10.8 Tg C yr-1 between 1982 and 1997, with an uncertainty of ± 40%. A simple index was developed to relate estimated SOC stocks to the potential amounts under native conditions and conventional agricultural management. An index value of 0% on the proposed scale would be equivalent to the SOC under conventional a gricultural use, while an index value of 100% would be equivalent to native levels. With an estimated 1997 stock of 22 400 Tg C, the index value for US agricultural soils was about 60%. Using this inventory procedure, environmental issues related to soil, water and air quality could be informed by SOC in combination with other key indicators, in addition to using the inventory for evaluating sustainability of agricultural lands for food and fiber production. Key words: Natural resource inventory, environmental quality indicators, soil organic carbon, land use and management, national inventory, Organization for Economic Co-operation and Develop

Impact of Soil Management and Two Botanical Insecticides on Urease and Invertase Activity

Yard waste compost provides an organic amendment useful for improving soil structure and nutrient status. The activities of the enzymes hydrolyzing urea (urease) and sucrose (invertase) in the rhizosphere of potato plants were determined under field conditions. Soil urease and invertase activities were monitored in compost amended soil, grass buffer strips, and in adjacent bare soils during 35 d following soil treatment. Soil urease activity was increased by application of yard waste compost compared to untreated soil which provide evidence of increased soil microbial population following application of compost. Some transitional effects on urease activities were observed following Pyrethrins and Neemix‐4E application, these effects were neither drastic nor prolonged enough to be considered deleterious to the soil microorganisms and their activities important to soil fertility. No relationship was found between invertase activity and the three management practices or soil organic matter content. It is suggested that application of botanical insecticides like pyrethrins and Neemix‐4E may be useful in delaying urea fertilizer mineralization to maintain N in a form less leachable, so that the duration of N availability to plants is prolonged. The present study may also provide information on urease activity as a sensitive bioindicator of soil quality that reflects the effects of land management on soil quality and may assist land managers in monitoring long‐term productivity and sustainability of agricultural lands.

Agricultural land use change and sustainable use of land resources in the mediterranean region of Turkey

Agricultural land use has changed in the Mediterranean Region particularly since the 1950s. Factors affecting these changes include increasing agricultural productivity and intensification, changes in population density, industrialization, urbanization, tourism, agricultural mechanization and use of agri-chemicals. Farms have been fragmented and the average farm size has decreased because of rapid rural population growth. During this period, most pasture and meadow land has been transformed into crop cultivation. Once productive farmlands have been used for industrialization, urbanization and tourist developments. For sustainable agricultural land use, new legal and institutional regulations are required, which integrate environmental concerns and agricultural policies. These regulations must be defined in terms of multiple use of agricultural land and strict conservation of prime agricultural land.

Assessment of the Condition of Agricultural Lands in Six Mid‐Atlantic States

AbstractIndicators of the condition and sustainability of agricultural lands covering 5.5 million ha in six mid‐Atlantic states were measured in 1994 and 1995. The primary objective was to collect baseline information against which future data from the region can be compared. Soil samples and questionnaire data were collected from a random sample of 293 sites. Indicators addressed productivity, management at the agroecosystem scale, and management for the landscape scale on annual crop land. Crop yields were almost 30% higher than those of the 1980s, with a mean observed to expected yield index of 1.27. The mean soil quality index showed moderate quality for supporting plant growth. Non‐tilled sites, which were mostly hay, had greater microbial biomass than tilled sites. Just over half of the annual crop land was covered by rotation plans; hay fields accounted for most of the land where one crop was grown continuously. Hay showed a lower use of applied nitrogen than seed crops. Integrated pest management was practiced on less than 20% of annual crop land. Twenty‐seven different annual crops were grown in the region, with hay (all types) the dominant crop. Less than 20% of the land where pesticides were applied had high to moderately high potential for pesticides leaching into ground water. This information provides a baseline for long‐term monitoring of agricultural lands in the region.

Livestock farming systems and sustainable drinking water production: proposition of risk indicators at different organisational levels

In the north-east of France, livestock farms, mainly dairy cattle farms, increasingly attempt to replace grass fodder by silage maize. This evolution of agricultural practices modifies the quality of groundwater for human consumption. We propose three indicators of diffuse nitrate pollution risk at three organisational levels: (i) the livestock unit: a ‘hydro-appraisal’ based on cattle feeding management is calculated for the dairy and the fattening units of the Experimental Research Station of Mirecourt, in order to compare the pollution risks due to the production schemes (dairy cows fed with grass against maize, beef steers fed with grass against beef calves fed with maize); (ii) the livestock farm: an indicator based on the cropping plan and on the mean nitrate leaching under the main cropping and grassland systems is calculated on twelve livestock farm types classified from 2211 farms in Lorraine, in order to identify the farming systems that present a pollution risk; (iii) the livestock farming region: the previous indicator is located at the French commune scale by taking into account the proportion of farm types and the relative farming area used by each type, in order to differentiate geographic areas according to the estimated pollution risk. The construction and the combining of such indicators contribute to the development of decision support tools for those concerned with water resource protection and sustainable agricultural land use in livestock farming regions.

Assessment of the Condition of Agricultural Lands in Five Mid-Atlantic States

Indicators of the condition and sustainability of agricultural lands in five Mid-Atlantic states were measured in 1994. Indicators were selected to reflect crop productivity and land stewardship on annually harvested herbaceous crop (AHHC) land, which covers almost 10% of the land area in this region. Overall, condition of agricultural lands in the region is good. Crops generally yielded more than those grown in the 1980s, with a mean observed/expected yield index greater than 1. The mean soil quality index was slightly better than a "moderate" rating for crop growth. Almost 2/3 of the AHHC land is covered by crop rotation plans, with the remaining land mostly in hay fields. Insecticides were applied to less than 20% of AHHC land, and less than 20% of the land where pesticides were applied has high to moderately high potential for pesticides leaching into groundwater. However, integrated pest management (IPM) is practiced on less than 20% of AHHC land. Hay showed more efficient use of nitrogen than seed crops, and non-tilled sites, which are mostly hay, had more microbial biomass (suggesting more nutrient cycling) than tilled sites. This information could provide a baseline for a long-term monitoring program for agroecosystems in the region.

Aggregate and organic carbon concentration interrelationships of a Torrertic Paleustoll

Good-quality soil is important for crop production sustainability of agricultural lands. An indicator of soil quality is the soil organic carbon (OC) concentration, which affects the soil dry aggregate (DA) and water-stable aggregate (WSA) size distribution. These, in turn, affect the soil quality. This study was conducted to establish relationships among various DA, WSA, and soil OC variables of a Torrertic Paleustoll (Pullman clay loam) using simple, polynomial, and multiple regression procedures. Samples were obtained from a depth of 0–3 cm of 18 differently managed dryland treatment areas or fields at Bushland, Texas, USA, to determine DA and WSA size distributions and OC concentrations of bulk soil. The water stability and OC of aggregates obtained by dry sieving were determined also. Areas sampled ranged from plots or fields cropped to winter wheat ( Triticum aestivum L.) and grain sorghum ( Sorghum bicolor (L.) Moench) for over 20 years to grasslands converted to cropland in 1994. Of the 110 relationships analyzed, 63 were significant at P ≤ 0.05 and another 23 were related at P levels of 0.10, 0.20, or 0.40. Variables involving the 0.84 to 2.0 mm DAs often were significantly related to various other DA and WSA variables and to soil OC variables, including a positive relationship with bulk soil OC. The DAs in this size range resist erosion by wind. Because of their significant relationship with WSAs, they are important also for maintaining water infiltration, thereby reducing the potential for erosion by water and increasing the potential for greater soil water storage. Practices such as reduced or no-tillage retain crop residues on the soil surface and thereby maintain or enhance surface soil OC concentrations, which enhance the development of DAs in this size range. By inference, these practices, therefore, are important also for maintaining production sustainability of Torrertic Paleustolls such as Pullman clay loam and similar soils.

Livestock, Deforestation, and Policy Making: Intensification of Cattle Production Systems in Central America Revisited

Objectives were to analyze arguments that extensive cattle production causes deforestation in Central America and to evaluate trade-offs among policy objectives implied by intensification of cattle production. Intensification of cattle systems is unlikely to alter dramatically the deforestation rates in Central America because consumer demand for livestock products is not the principal factor motivating most migration to forest areas. Rather, many migrants are from resource-poor households and are seeking survival at the forest margin. Policies to slow deforestation need to improve economic opportunities for the rural poor and to promote sustainable agricultural land use through technologies that farmers will adopt. Policies to promote intensification need to recognize the role of existing extensive cattle systems, the technical limitations and opportunities that are associated with different types of intensification, and the trade-offs between objectives of producers and policy makers. Depending on the policy trade-offs, intensification of existing production systems, such as the dual purpose system, may be preferable to substitution of specialized technologies from temperate countries. More information is required about production possibilities, social impacts, and the trade-offs among various strata of farmers and consumers to formulate better livestock policies for Central America.

Assessing the sustainability of agricultural land in Botswana and Sierra Leone

AbstractLand degradation processes, such as soil erosion, which threaten the sustainability of agricultural production have been studied for many years. While research progresses on the processes, little advance has been ade on translating results into terms which can be used directly in the design of appropriate and economically justified forms of soil conservation and land husbandry.Research by the authors has shown how soil erosion affects the potential of land to produce crops. Simple models have been developed which provide a first approximation of the impact of soil erosion on future production, to be used as a baseline against which the benefits of soil conservation can be compared. The concepts of soil life and residual suitability have been developed as a measure of the sustainability of the production system considered. In this paper a simple experimental technique to derive the future production and the residual suitability of land is proposed.The method is based on the principle of sequential testing and uses a simple graphical technique to translate information on production and erosion into a crop production forecast. The soil life or residual suitability of land is derived from the minimum allowable crop production which depends on socio‐economic criteria. In case the minimum allowable production level cannot be reliably estimated, the concept of production ‘half‐life’ is introduced as a relative measure of sustainability. The method and its applications are illustrated using examples from Botswana and Sierra Leone.

Land use, economy and ecology: Needs and prospects for co-evolutionary development

This article examines new developments which may pose a threat to coevolutionary development in Europe, and scrutinizes in particular the current agricultural policies of the European Community (EC). With the help of a threefold typology—ecological, traditional and modern—the likely perceptions and behaviour of farmers in the face of external change are discussed. On this basis the authors identify research needs, and draw up an extensive research agenda which will have to be addressed if ecologically sustainable agricultural development and land use are to be promoted.