Modelling the dynamics of sheep flocks in Egypt

A structured multi-period Goal Programming model for the determination of the optimal age structure of a flock of sheep given a set of sheep breeder goals is used to evaluate three sheep breeding flock cases in Egypt. The cases are: flocks with a fixed size over an arbitrary period of 5 years, flocks with a growing size over the same period and flocks with a fixed size and stable age structure over time. The breeder's goals considered are the total increase of kilograms weaned and the total wool produced by the flock, the decrease of the average flock age and the flock initial purchase cost.The model was applied on the local Rahmany Egyptian sheep. Results for the three considered cases are presented and discussed.     

Quantifying the sustainability of agriculture

The rural sustainability index is a scientifically based tool to quantify the performance of agriculture. The sustainability of crop production is quantified from three perspectives; people, planet and profit. Within each perspective, one condition was selected that must be met to warrant agriculture. These are: No hazardous work should be used within the crop production chain; agricultural crops should not be grown on land allocated to nature by national law or regulations and, when a GM-crop is present or is introduced in a region, it should not harm development opportunities of other farmers. If these excluding conditions are met, the sustainability of agriculture is assessed through five performance indicators on school attendance, water use and consumption, fertilizer use, pesticide use, and farm income. For each of the five indicators, critical values and target values have been given that limit the transition range between non-sustainable and sustainable production. The five indicators are combined into a sustainability index. The index aims at improving the socio-economic position of farmers while protecting the environment.

Risk and economic sustainability of crop farming systems

In economic terms, resilience in farming has to do with the capacity of a farm business to survive various risks and other shocks. Despite its importance, resilience has seldom been directly considered in evaluations of economic sustainability. A whole-farm stochastic simulation model over a 6-year planning horizon was used to analyse organic and conventional cropping systems using a model of a representative farm in Eastern Norway. The relative economic sustainability of alternative systems under changing assumptions about future technology and price regimes was examined in terms of financial survival to the end of the planning period. The same alternatives were also compared in terms of stochastic efficiency. To model the risk of business failure adequately there is a need to deal with the risk of bankruptcy, and a modification of traditional analysis was used for that purpose. The organic farming system was found to be somewhat less economically sustainable than the conventional system, especially if the organic price premiums and the organic area payments were to be phased out. The results illustrate possible conflicts between pursuit of risk efficiency and economic sustainability. The model developed could be used to support farmers’ choices between farming systems as well as to help policy makers develop more sharply targeted policies.     

Application of a simulation model for assessing integration of smallholder shifting cultivation and sheep production in Yucatán, Mexico

Simulation models are effective tools to examine interactions between livestock, cropping systems, households, and natural resources. Our study objective was to use an integrated livestock and crop model to assess the outcomes from selected suites of management decisions observed in smallholder sheep-cropping systems of Yucatán, Mexico. The scenarios contrasted specialized systems versus mixed farming, and evaluated the outcomes of increased crop-livestock integration. Mixed enterprise scenarios involving sheep provided more income than specialized enterprises, and capitalized on a lower price of on-farm maize grain, efficient utilization of surplus labor, and availability of common land. Labor and management income was greatest for the unintegrated and partially integrated crop and livestock scenarios. It was more profitable for producers to sell excess grain and maize stover, and use common land to feed the livestock, suggesting that increased integration does not always result in improved outcomes. The results are consistent with a system not yet pushed to the point where integration is inevitable. For all sets of scenarios, the model structure was able to accommodate subtle management differences to produce appropriate biophysical, labor, and economic outcomes. We conclude there is potential to use similar model development methods to describe other crop-livestock systems, thus providing tools for learning, scenario analysis, and impact assessment.     

Environmental performance in the US broiler poultry sector: Life cycle energy use and greenhouse gas,ozone depleting,acidifying and eutrophying emissions

Most published research concerning the environmental impacts of broiler poultry production is limited to assessments of on-farm gaseous and nutrient emissions. Here, ISO-compliant Life Cycle Assessment was used to predict the broader, macroscale environmental impacts of the material and energy inputs and emissions along the US broiler supply chain. It was found that feed provision accounts for 80% of supply chain energy use, 82% of greenhouse gas emissions, 98% of ozone depleting emissions, 96% of acidifying emissions and 97% of eutrophying emissions associated with the cradle-to-farm gate production of broiler poultry. On-farm inputs and emissions, largely related to heating and ventilation contribute on average only 9% of these impacts. These results underscore the fallacy of “landless farming” and the importance of full supply-chain environmental management for improving sustainability in the US poultry industry.     

Development and evaluation of an integrated simulation model for assessing smallholder crop-livestock production in Yucatán, Mexico

Mixed farming systems constitute a large proportion of agricultural production in the tropics, and provide multiple benefits for the world’s poor. However, our understanding of the functioning of these systems is limited. Modeling offers the best approach to quantify outcomes from many interacting causal variables in these systems. The objective of this study was to develop an integrated crop-livestock model to assess biophysical and economic consequences of farming practices exhibited in sheep systems of Yucatán state, Mexico. A Vensim™ dynamic stock-flow feedback model was developed to integrate scientific and practical knowledge of management, flock dynamics, sheep production, partitioning of nutrients, labor, and economic components. The model accesses sheep production and manure quantity and quality data generated using the Small Ruminant Nutrition System (SRNS), and interfaces on a daily basis with an Agricultural Production Systems Simulator (APSIM) model that simulates weather, crop, and soil dynamics. Model evaluation indicated that the integrated model adequately represents the complex interactions that occur between farmers, crops, and livestock.     

Assessing multi-criteria approaches with environmental, economic and social attributes, weights and procedures: A case study in the Pampas, Argentina

Soil erosion control is a major issue in agriculture. The no till system of soybean production has been widely adopted; however, soil erosion may increase due to pasture and forestry land convertion to cropland in the marginal Pampas, Argentina. The aim of this paper is to assess the conflicts and trade-off among environmental, economic and social interests by using three continuous multi-criteria approaches and a set of different weights. Different land uses, crops, pastures, forestry and soil and water conservation practices at the basin scale in the marginal Pampas were assessed. The basin (423 km²) was discretised into 176 sub-basins to focus the management strategy on 5th and 6th order streams. Minimum basic information was obtained using intensive field observations and satellite images. The basin hydrology, soil erosion, sediment delivery and vegetated filter strip models and GIS were used to quantify the technical coefficients. Thirteen decision factors and six criteria (peak run-off, annual erosion, sediment, investment, gross margin and employment) were used in the optimisation trials. Weighted goal programming, lexicographic goal programming, compromise programming and a sensitivity analysis of weights were performed. The results showed a high impact of soil and water management practices on the environmental factors and a strong conflict between environmental and economic interests. The three multi-criteria approaches also showed that it is possible to obtain a good level of goal achievement with different plans. These plans should include: soil conservation practices; crop rotation (of a 2:1 soybean-to-corn ratio); gully and channel erosion control; regulation ponds; and pasture and agro-forestry areas. This goal achievement is mainly limited by public and private investment. Sensitivity analysis of the decision-maker weights shows differences among the values achieved by the criteria and their trade-off. Thus, the weight value of each criterium should be supported by the negotiation-consensus process.     

牛羊养殖场剩料收集机设计与试验

针对目前我国牛羊养殖场饲喂过程中饲喂通道存在剩余饲料的问题,设计一种代替人工收集剩余饲料的剩料收集机。该机主要由盘刷、收料装置、输送装置、集料箱等部件组成。收集机通过前端的盘刷,将剩料清扫到收集机的清扫方向上,再利用圆柱刮板、螺旋圆柱刷、两侧绞龙将剩料输送到吸口处,利用链条、刮板将剩料输送到剩料箱。重点对盘刷清扫装置、螺旋圆柱刷、螺旋集料机构、链条刮板机构和液压系统等关键部分进行设计计算,确定盘刷的旋转速度为150 r/min,螺旋圆柱刷的转速为80 r/min,螺旋绞龙的转速为60 r/min,剩料收集机的前进速度为5 km/h。在实际试验中,剩料收集率均在96%以上,平均收集率达到97%,收集机收料效果良好,达到牧场的使用要求,验证了本设计的正确性。     

Comparison of measured and simulated water storage in dryland terraces of the Loess Plateau, China

In the hilly regions of China, developing sustainable agriculture requires implementing conservation management practices that prevent soil erosion and conserve soil and water resources. In the semiarid northwest Loess Plateau, the primary conservation management practice is terracing. Numerical simulation of soil water dynamics in terraces is potentially an efficient means of investigating the effects of terrace design on moisture retention, but little information is available on the accuracy of such simulations. In this work, we evaluated the accuracy of HYDRUS-2D simulations of water infiltration and redistribution in fallow, level, dryland terraces located in the Loess Plateau. The simulated soil water content distributions were in good agreement with experimental data. Modeling analyses showed that about one-third of the evaporative water losses occurred from the terrace riser surface. To prevent such losses, it is advisable to mulch the riser and minimize the riser surface area. The simulations also demonstrated that with other dimensions equal, wide terraces retain more water on a percentage basis than narrow ones due to a lower evaporating surface area are per unit volume of water storage. With other design considerations being equal, wide beds and minimal riser surface areas will likely enhance water capture and retention. Future analyses of terrace moisture dynamics may additionally include simulations of root water uptake, surface ponding, and runoff.     

Land use change patterns and livelihood dynamics on the slopes of Mt. Kilimanjaro,Tanzania

This study is about changes in land use and interactions of land use change and livelihoods in the Chagga farming system on the slopes of Mt. Kilimanjaro, Tanzania. An aerial photo interpretation and fragmentation analysis of the years 1961, 1982 and 2000 was conducted covering approximately the Kirua Vunjo Division, a transect of 152 km² from the forest reserve edge to the plains. Earlier changes were traced from literature review. The results show the expansion of cultivation to more marginal land down the slope, the disappearance and extreme fragmentation of bush land and appearance and expansion of settlements. The home garden area has experienced some specific internal change, but has not expanded down the slope. In the 1960s there were small open fields and patches of grazing lands amongst home gardens. In the 1980s the area was more uniformly covered by homegardens. Since then it has become patchy again as new homesteads have been built on subdivided farms and more food is produced on the higher slopes. Population pressure and the ensuing expansion of agriculture to more marginal land, intensification of the homegarden system, together with climate changes affecting the water supplies, have caused changes in farmers’ livelihoods. As land scarcity now hinders expansion of agriculture, farm size has seriously decreased, common resources have become scarce, and prices of coffee in the world market remain low, farmers are trying to intensify and diversify their farm production. Local initiative is leading to change, but the locally conceived alternatives are too few and lack integrated approaches of technical agricultural research, economic analysis, and policy studies and reforms. Non-agricultural activities and paid employment are becoming increasingly important. However, due to considerable entry barriers to remunerable off-farm jobs, not all households enjoy equal access to attractive non-farm opportunities. The future welfare of the area will depend on increasing the marketable knowledge and skills of the population that will enable it to become integrated in the economy of the region and the country.     

Assessing the groundwater dynamics and impacts of water saving in the Hetao Irrigation District, Yellow River basin

Water resources allocated to the agricultural sector in the Yellow River basin are being reduced due to severe water scarcity and increased demand by the non-agricultural sectors. In large-scale irrigation districts, the application of water-saving practices, e.g., improving the canal system, using water-saving irrigation technology and adjusting cropping patterns, is required for the sustainable agricultural development and the river basin environmental equilibrium. Adopting water-saving practices leads to lowering the groundwater table and to controlling salinity impacts related to excessive irrigation. However, assessing the effects of water-saving practices on the groundwater system requires further investigation. The Jiefangzha Irrigation Scheme of the Hetao Irrigation District is used as a case study for analyzing the temporal and spatial dynamics of the groundwater table. A lumped parameter groundwater balance model has been developed with this purpose and to assess impacts of various water-saving practices. The model was calibrated with monthly datasets relative to the non-frozen periods of 1997-1999 and validated with datasets from 2000 to 2002. Results indicate that canal seepage and deep percolation account for respectively 48% and 44% of the annual groundwater recharge. Groundwater discharge by direct evaporation and plant roots uptake represents 82% of the total annual groundwater discharge. After validation, the model was applied to assess the impacts of various canal and farm irrigation water-saving practices. It was observed that improvements in the canal system (e.g., canal lining, upgrading the hydraulic regulation and control structures, improving delivery schedules) might lower the groundwater table by 0.28-0.48 m, depending upon the level of implementation of these measures. Higher declines of the groundwater table are predicted when water-saving technologies are applied at both the canal and the farm systems. That decline of the water table favours salinity control and reduces capillary rise, thus reducing the groundwater evaporation and uptake by plant roots; that reduction may attain 128 mm. However, predictions may change depending on the way how water-saving measures are applied, which may be different of assumptions made; therefore, there is the need to perform a follow-up of the interventions in order to update predictions. Results indicate the need for appropriate research leading to improved irrigation management when the decline of the groundwater level will reduce groundwater contribution to vegetation growth.     

Impacts of population growth, economic development, and technical change on global food production and consumption

Over the next decades mankind will demand more food from fewer land and water resources. This study quantifies the food production impacts of four alternative development scenarios from the Millennium Ecosystem Assessment and the Special Report on Emission Scenarios. Partially and jointly considered are land and water supply impacts from population growth, and technical change, as well as forest and agricultural commodity demand shifts from population growth and economic development. The income impacts on food demand are computed with dynamic elasticities. Simulations with a global, partial equilibrium model of the agricultural and forest sectors show that per capita food levels increase in all examined development scenarios with minor impacts on food prices. Global agricultural land increases by up to 14% between 2010 and 2030. Deforestation restrictions strongly impact the price of land and water resources but have little consequences for the global level of food production and food prices. While projected income changes have the highest partial impact on per capita food consumption levels, population growth leads to the highest increase in total food production. The impact of technical change is amplified or mitigated by adaptations of land management intensities.     

Feed resources,livestock production and soil carbon dynamics in Teghane,Northern Highlands of Ethiopia

In the Northern Highlands of Ethiopia, integrated crop-livestock production within smallholder farms is the dominant form of agricultural production. Feed availability and quality are serious constraints to livestock production in Ethiopia in general, and in its Northern Highlands in particular. The objective of this study was to describe the relationship between feed availability and quality and live weight gain, milk and manure production and the soil C balance in Teghane, Northern Highlands of Ethiopia. The so-called JAVA model procedure, that essentially predicts metabolizable energy intake and animal production on the basis of feed quality and quantity, has been used and linked to a soil carbon balance. Forages were ranked according to their quality (on the basis of metabolizable energy intake by livestock) in descending order. Rations were formulated by stepwise including components of increasingly lower quality to calculate the trade-offs between feed quantity and quality. In the model, the soil C balance was described in relation to soil organic matter decomposition, C input from roots, grazing and/or harvesting losses, feed residues and manure. Moreover, an analysis of monetary values of live weight gain/loss, manure and draught power is included. The results of the model showed that mean daily live weight gain and milk production per TLU continuously increased with decreasing herd size, while total annual live weight gain reached a maximum (62 Mg) at the use of the 30% best feeds and a herd size of 630 TLU. Soil C balance at this level of feed use is negative and deteriorates with increasing feed use. The model estimated an optimum herd size of 926 TLU to attain the maximum combined monetary value of live weight gain, manure and draught power at 50% feed use. Actual herd size in the study area was 1506 TLU. Our results indicate that in areas where feeds of very different quality are available, maximum benefits from meat and/or milk production and soil C balance can be attained by selective utilization of the best quality feeds, through a storage and carry-over system.     

Outflow reduction and salt and nitrogen dynamics at controlled drainage in the YinNan Irrigation District, China

The YinNan Irrigation District in NingXia, China diverts each year about 1.6 × 10⁹ m³ water from the Yellow River for irrigation use. More than half of that water is discharged back to the downstream channel or some low-lying depressions as a result of agricultural drainage. Several studies have indicated that the District is excessively drained, partially caused by the over-dimensioning of the existing drainage system, and proposed to improve the situation by controlled drainage practice. We subsequently carried out a field experiment of controlled drainage in the rice growing area of the District in 2004–2005. Field observations showed that reduction of the drainage depth of field ditches from 1 to 0.4 m resulted in a drainage flow reduction of 50–60%. Drainage water salinity increased only slightly but was still below the salt tolerance level of rice. Measurements of nitrogen concentrations showed no clear trend of changes as the result of irregular fertilization practice in the experimental site.     

Poverty dynamics and the role of livestock in the Peruvian Andes

Livestock play an important role for poor rural households in regions such as the Peruvian Andes. Research methods leading to a better understanding of the role of livestock in household poverty dynamics, and what better targeted policies and interventions may enhance that role, however, are not readily available. We utilized multiple methods, including Stages-of-Progress and household surveys, which gave us a combination of qualitative and quantitative results. We examined how over the last 10 and 25 years households have moved into and out of poverty in 40 rural communities in two different highland regions of Peru. We also examined the role played in these movements by different livestock assets and strategies. We found a significant number of households had escaped poverty, while at the same time many households have fallen into poverty. The reasons for movements up versus down are not the same, with different strategies and policies needed to address escapes versus descents. Diversification of income through livestock and intensification of livestock activities through improved breeds has helped many households escape poverty and this method allowed us to explore what exactly this means in the diverse areas studied. These findings can contribute to better targeted livestock-related research and development strategies and policies, not only in Peru, but in other regions where similar livelihood strategies are being pursued.     

Ten consecutive years of regulated deficit irrigation probe the sustainability and profitability of this water saving strategy in loquat

The successful application of postharvest regulated deficit irrigation (RDI) over ten consecutive years (from season 1999/2000 to season 2007/2008) confirms the sustainability of this strategy for producing ‘Algerie’ loquat. Postharvest RDI consisting in a reduction of watering (between 45 and 80% depending on the season) from early June until the end of August, improved loquat profitability by increasing fruit value and by reducing water consumption with respect to fully irrigated trees (control). The increase in fruit value in RDI trees was due to a consistent improvement in harvest earliness as a result of an earlier blooming. Water savings of around 20% did not diminish yield nor fruit quality. Water use efficiency in RDI trees rose by over 30%. Water productivity reached 9.5 € m⁻³ of water applied in RDI trees versus 6.6 € m⁻³ in control trees. The most noticeable effect of RDI on vegetative growth was a significant and progressive decline in trunk growth. The canopy volume seems to be strongly influenced by pruning and no significant effects were detected in this parameter. Our results confirm the suitability of RDI in loquat and the economic benefits of saving water during the summer.     

CAD线图数据处理的GM(1,N)模型与方法

运用灰色系统理论，通过优化模型系数与背景取值建立了灰色多因素灰色动态GM（1，N）模型。该模型克服了现有GM（1，N）模型的不足，扩宽了GM（1，N）模型的应用范围。运用该模型的GM（1，2）、GM（1，3）线图处理实例表明该方法简单实用，值得在计算机辅助设计中推广应用。     

农业机械装备数量预测模型的研究与应用

科学地预测对于决策具有重要的作用。为此,针对农业机械装备发展所需,选择基于时间序列的预测模型对我国单位耕地面积上农业机械装备数量进行预测,以期为农业机械化发展的研究和决策提供科学的方法和理论依据,为我国农业机械化事业工作者提供一定的参考。     

温室小气候环境模型的应用及综述

对国内外温室小气候环境建模方法的研究进行了综述。温室小气候环境建模的方法主要有两种:一是以能量平衡方程和质量平衡方程为理论依据研究温室的模型,另一种方法为基于输入输出数据的模型,包括线性模型、非线性模型、黑箱模型等。同时,指出了目前温室小气候建模方法存在的问题,并对温室小气候环境建模方法的发展趋势进行了展望,并介绍了一种温室小气候建模方法在气候自适应PID控制中的应用。     

Balancing land use to manage river volume and salinity: Economic and hydrological consequences for the Little River catchment in Central West, New South Wales, Australia

It has been widely suggested that changing land use from annual to perennial crops reduces land and stream degradation due to salinisation. However, annual crops are financially attractive and increases in perennials can reduce stream flows with adverse effects on stream values. As such, salinity control is likely to involve tradeoffs between public and private costs and benefits. This study quantifies the expected on-farm economic and catchment-level water yield and salinity effects of altering land use among trees, perennial pastures and cereals. The structure of a two stage linear-programming (LP) process is described. The first stage is the MIDAS farm-level model of mixed cropping and sheep enterprises which provides inputs to a second stage catchment-level LP. It was concluded that perennial pastures can be used in conjunction with trees as a stream salinity-management tool in low to intermediate rainfall areas in New South Wales. The results indicate that land-use decisions should be informed by site-specific information if adverse effects on streams are to be avoided.