Feed conversion efficiency and the efficiency of the UK food chain

The efficiency of transfer of food energy across various components of the human food chain is calculated for the UK. The processing and presentation stages have overall efficiencies of transfer of 0·75 and 0·93, respectively, with foods of animal origin mainly showing higher efficiencies of transfer through these processes. The efficiency of agriculture, related to a hypothetical maximum potential biomass production, is 0·026, with relatively lower efficiencies for the livestock industries. Yields of food energy from crops and livestock in the UK are calculated as 33 and 4 GJ per hectare, respectively. The factors affecting animal feed conversion efficiency are examined and it is shown that there is a potential conflict between high animal feed conversion and overall food chain efficiency. The consequences of this conflict—and possibilities for optimisation—are examined in terms of a simple resource allocation model.     

The economics of low pressure drip irrigation and hand watering for vegetable production in the Sahel

Low pressure drip irrigation is being promoted in Sub Saharan Africa as an alternative to traditional methods of small scale irrigation of vegetables. The African Market Garden (AMG) is a horticultural production system for smallholders based on low-pressure drip irrigation combined with an improved crop management package. The agronomic and economic performance of the AMG is compared to two gardens irrigated manually with watering cans. One of these gardens is managed according to the same improved crop management package as in the AMG, this treatment is called Improved Management (IM). The other garden is managed according to common practices of vegetable producers in the area, this treatment is called the Farmer Practice (FP). Crop productivity, labor and water use were monitored for two vegetable species (okra and eggplants). The experiment was performed on-station in Niger on three adjacent 500 m² plots in a sandy acid soil. It was found that improved crop management practices greatly enhance crop productivity over traditional methods at comparable production costs. The AMG gave higher crop yields and higher returns to investment than the treatments irrigated with watering cans. Labor accounts for up to 45% of the production cost in vegetable gardens irrigated by hand, where 80% of the producer time is spent on irrigation. The total labor requirement for the drip irrigated AMG was on average 1.1 man hours per day against 4.7 man hours per day for the Farmers Practice on a 500 m² garden. Returns on labor are at least double for the AMG against the other treatments. The returns on land from eggplant were found to be US$ 1.7, 0.8 and 0.1 per m² for the AMG, IM and FP respectively. The returns on water for the cultivation of eggplant are around US$ 2 per m³ in the AMG, against US$ 0.1 in the Farmers Practice. This experiment showed the strong positive impact of drip irrigation and improved crop management practices on profits at minimal environmental costs, indicating that transformation of existing practices poses a considerable potential towards sustainable agricultural development.     

An analysis of supply response among cotton growers in Malawi

Cotton is a traditional smallholder cash crop in Malawi. Its production in recent years has stagnated as the area under the crop has declined considerably since 1975. Much of the criticism for the stagnant production and declining acreage has been levelled at producer prices. This paper investigates the responsiveness of cotton producers to changes in these producer prices. A Nerlovian partial adjustment model is used to test the response. The results indicate that producers are responsive to price incentives but that their response is inelastic. Both short- and long-run price elasticity estimates are less than unity (0·13 and 0·46, respectively) and the coefficient of adjustment which measures the speed of adjustment is only 0·212. Prices of cotton and competing crops, area under cotton in the preceding season and weather conditions are found to be important factors to the producers in their land allocation decision making process.     

Analysis of and Experimental Measurements made on a Moving Air-Assisted Sprayer with Two-Dimensional Air-Jets Penetrating a Uniform Crop Canopy

Air-assisted crop sprayers use air-jets to enhance the transport and deposition of agricultural pesticides in crops that are difficult to spray using conventional equipment. However, the use of air-jets can cause excessive environmental contamination or give an ineffective treatment if the flow characteristics are poorly matched to the target crop. To establish a scientific basis for improving the design and control of air-assisted sprayers, this paper presents an analysis of the momentum and turbulent kinetic energy conservation equations for a two-dimensional air-jet penetrating a uniform crop canopy from a moving sprayer. From the analysis of these equations the velocity and turbulent kinetic energy along the jet centre-line are shown to decay exponentially with penetration distance. The decay exponents are shown to be proportional to the inverse of the jet width, the square of the ratio of sprayer speed to initial air-jet velocity and the crop density. Velocity and turbulence kinetic energy measurements are presented for a two-dimensional air-jet penetrating an artificial crop canopy. The canopy was constructed from a regular array of flow blockage planes which were adjusted to give an experimental range for area density (i.e. the cross-sectional area of blockage normal to the initial air-jet flow direction per unit volume) between 0·7 m^-1and 3·0 m^-1for two different values of plane spacing of 0·23 m and 0·46 m.The experimental results verify the exponential decay form for the distributions of air flow properties along the jet centre-line. The values derived for the exponential decay coefficient for both jet centre-line velocity and turbulent kinetic energy were found to give a poor correlation with the canopy area density over the full range of experiments. Instead, this correlation exhibited an asymptotic characteristic as the exponential decay coefficients for mean centre-line velocity and turbulent kinetic energy become very large at finite area density during high planar blockage. A rationale for this additional effect of crop structure is presented in terms of the additional losses produced by local flow channelling within dense canopies. The asymptotic characteristic was successfully modelled by redefining the crop density as the weighted sum of the inverse of the two orthogonal mean flow gaps in the artificial crop canopy. This new form of crop density replaces area density in an otherwise conventional model for momentum and turbulent kinetic energy losses due to small-scale volume averaging of air-jet and crop interactions.     

我国秸秆加工机械的发展分析

随着国家恢复生态建设、实施禁牧圈养,秸秆对于牲畜的饲喂显得尤为重要.目前,我国每年生产的秸秆达6亿t多,占全世界秸秆总产量的20%～30%,是饲料的重要来源.近年来,我国畜牧业的快速发展对饲草的需求量急剧上升,有力地促进了饲草业的发展,同时也带动了饲草机械化的发展.大力发展牛、羊等食草动物,合理利用秸秆资源,促进饲草收贮和草产品加工技术,直接关系到国民经济的可持续发展.为此,论述了我国秸秆资源的利用情况,分析了秸秆加工机械及其发展现状,指出了秸秆加工机械的发展趋势.     

Evaluating crop-livestock-based farming systems: A village level study in the dry zone rainfed district of Sri Lanka

In Sri Lanka cropping enterprises interact with livestock production on peasant farms. This analysis of the crop-livestock farming system aims at understanding the existing constraints and interactions between crops and livestock in these farms. The main objective of the study is to describe the crop-livestock integrated farming systems in three rainfed villages in the Moneragala district of Sri Lanka, and to evaluate these systems in terms of maximizing farm incomes from the different crop and livestock components of the systems. A field survey was conducted to collect data from 153 farming families for the Maha season of 1982/83. A linear programming model was formulated to test the hypothesis.The results show that in general the activities for lowland rice, highland rice, sugar cane, labour, farm cash cost, and MVP (compost) are higher in the optimal farm plan than in the actual farm situation. The livestock in the optimal plan is mainly confined to milch cattle. However, with the present high level of manutrition among rural livestock industry emphasis should be placed on the expansion of the rural livestock industry in the study villages. The optimal plan also suggests the use of crop residues as a substitute for compost for farm crops. Hence, in the context of escalating prices of chemical fertilizers, research is required to find the suitability of crop residues and household residues as substitutes for compost. Increases in supplementary irrigation may result in the expansion of the farm area and hence the farm income. Other methods of increasing farm income include: replacing hired labour with non-utilized family labour, increased agricultural research, and extension activity regarding the use of modern inputs by farmers on crops.     

A Review of Agronomic Factors Influencing Grass Silage Effluent Production in England and Wales

Silage effuent has a high biochemical oxygen demand (BOD) of about 60 000 mg/l. In 1991 it was estimated that the 29·7 Mt of bunker silage made per annum produced about 1·5 Gl of effluent. Silage effluent production is, however, extremely variable and may account for 25% of total agricultural water pollution incidents in wet years compared to 14% in dry harvest years. Incidents are highest in the grassland livestock areas of the west and least in eastern and south-eastern areas.A major factor in the increased pollution in recent years is the five-fold increase in the amount of silage made in the last 20 years. The average dry matter (d.m.) content of farm silages has also declined from about 270 to 250 g/kg in the past decade. Other reasons for increased pollution are inadequate and poorly maintained silos, crops being cut earlier and more late season aftermath cuts being taken in the autumn. There is evidence that increased use of nitrogen (N) fertilizer and N applied late produces grass with a low d.m. content. When this is ensiled with acid additives, effluent production is increased, but the effects of consolidation and mechanical pre-treatment are not clearly established. Large overfilled silos and poor silo design, structural deterioration and overflowing effluent tanks have also markedly contributed to silage effluent pollution.Effluent pollution could be reduced if crops were wilted to greater than 250g of d.m./kg. There are, however, difficulties in wilting in the wetter, western areas where rainfall and humidity are particularly high. The use of root and green crops together with higher d.m. crops for ensilage e.g. forage maize and whole crop cereals could potentially reduce effluent pollution; the present acreage is, however, very small in comparison with grass.     

Economics of drip irrigation of olives in Turkey

Agricultural growers need investment and cost guidelines for drip irrigation to evaluate the economics of getting crops into production as quickly as possible and to minimise economic losses from drought during the productive life of an olive orchard. The benefits of irrigation may include; better olive survival, earlier crop production, greater yields, efficient nutrient distribution, less plant stress, reduced yield variability and improved crop quality.This research was conducted to help olive growers make decisions regarding investments in drip irrigation systems. This analysis was aimed at the farm business level to provide an economic rationale for investing in drip irrigation systems.The net present value (NPV) criterion was used to determine the discounted break-even investment results from published responses to drip irrigation systems. Growers with typical drip irrigation systems can expect investments of US$ 2244 ha⁻¹ with 1.6 ha blocks of olives. Analysis of survey findings indicate that net present value was US$ 3464 ha⁻¹ after an initial investment of US$ 2244 ha⁻¹.     

An analysis of the efficiency of the UK food system

This paper presents a statistical analysis of the UK's food supplies in order to indicate the size of the problem of food losses and therefore to illustrate the potential savings.The energy and protein value of the food leaving UK farms and ports for consumption in the UK is estimated to be: Energy: 385 J × 10⁵ per annum Protein: 3·2 million tonnes per annum By comparison the energy and protein needs of the entire UK population are: Energy: 200 J × 10¹⁵ per annum Protein: 1·2 million tonnes per annumThe UK food system is losing a considerable proportion of the food material which is available for consumption in the UK. Much of this loss occurs during the primary processing prior to the food ‘moving into consumption’. The loss at this stage amounts to: Energy: 116 J × 10¹⁵ per annum Protein: 1·5 million tonnes per annumThe authors discuss the implications of this loss of efficiency and give generalised reasons for its occurrence.     

Exploring changes in world ruminant production systems

In the past 30 years world production of ruminant meat and milk has increased by about 40%, while the global area of grassland has increased by only 4%. This is because most of the increase in ruminant meat and milk production has been achieved by increasing the production in mixed and landless production systems and much less so in pastoral systems. Pastoral systems depend almost exclusively on grazing, while mixed and landless systems rely on a mix of concentrates (food crops) and roughage, consisting of grass, fodder crops, crop residues, and other sources of feedstuffs. A model was developed to describe these two aggregated production systems for different world regions, each having typical production characteristics, such as milk production per animal for dairy cattle, and off-take rates and carcass weights for non-dairy cattle, sheep and goats. The energy needed by the animals for the production of meat and milk is calculated on the basis of requirements for maintenance, grazing and labour, pregnancy, and lactation. We implemented the FAO Agriculture Towards 2030 projection for crop and livestock production and assumed that the past trend in the area of grassland will continue in the coming three decades. This assumption implies a rapid intensification of grassland management with a 33% increase in global grass consumption, which will only be possible with increasing fertilizer inputs, use of grass-clover mixtures and improved grassland management.     

河北省县域农田畜禽承载量与畜禽养殖量时空耦合

通过农作物种植面积计算农田畜禽承载量,并利用各类畜禽产排污系数估算区域畜禽理论养殖量,分析1994、2003、2013年河北省县域农田畜禽承载量与畜禽实际养殖量的变化态势及其耦合关系。研究表明:农作物播种面积呈现小幅波动态势,总量增加了83 663 hm2,以氮元素计的畜禽承载能力提高了108.7万头(猪当量);畜禽实际养殖量先增后减,总量增加了1 102万头(猪当量)。在仅考虑农作物种植面积消纳畜禽粪便的情境下,1994—2003年河北省有69个县市属于畜禽超载状态,有94.24%的县市生态持续衰退;2003—2013年农作物畜禽承载状况改善明显,超载的县市有26个,只占全省的18.7%。基于Ward聚类分析方法,将1994—2013年畜禽养殖量与农作物播种面积变化的耦合类型特征划分为9大区,提出了不同调控对策。     

Shallow flow of water through non-submerged vegetation

The shallow movement of water flowing through dense crops of wheat was studied for different crop densities and sowing patterns and ages. The common application of Manning's equation to such flows is shown to be inadequate, particularly since the flows can be described as mixed rather than turbulent.The more general discharge-depth equation has advantages for coping with the conditions, and relevant values of the parameters are provided both for (slope)^0·5 as well as for a suggested (slope)^0·35     

Yield,quality and profitability of sensor-controlled irrigation: a case study of snapdragon (<Emphasis Type="Italic">Antirrhinum majus</Emphasis> L.) production

Advanced wireless irrigation sensor networks that can monitor and control irrigation are only recently available commercially, but on-farm research has found a number of advantages compared with current irrigation practices including reduced water application, disease incidence, production time and labor, together with increased profitability. We examined the effects of wireless sensor networks to precisely control irrigation based on substrate moisture in a 0.15-ha greenhouse producing cut-flower snapdragons (Antirrhinum majus). We calculated changes in yield, production time, quality, cost, revenue and profit using grower data on production, expenditures and sales, which included 3 years of data before and after implementation of sensor irrigation networks. Sensor-based irrigation was associated with a 62 % ($65,173 or $434,487 ha^?1) increase in revenue and a 65 % ($35,327 or $325,513 ha^?1) increase in profit per year. Sensor-based irrigation was also associated with increases in the quality and the number of stems harvested per crop. The time to first harvest and time to last harvest were reduced for all cultivar groups, indicating that the plants grew faster using sensor networks. Production time per crop was decreased, allowing 2.5 additional crops per year. Electricity usage was also reduced, likely due to less frequent irrigation using sensor networks. These results are in line with other benefits we have seen by installing sensor networks in other types of ornamental operations.     

A model for recycling of feed nutrients in a crop,animal and biogas system in India

In northern India, with triple cropping intensity of fodder crops and recycling of feed nutrients in a milch animals and biogas system, from 1 ha of land it is possible to produce 82·63 GJ of energy and 906·11 kg of protein from milk; 263·93 kg of N; 148·93 kg of P₂O₅ and 90·94 kg of K₂O fertilizer from biogas slurry and 2897 kilowatts of power per annum for farm operation from biogas using the Kirloskar biogas engine. Traditional systems of wheat and rice cultivation can produce 93·87 GJ of energy and 654·25 kg of protein from food grain per hectare per annum. The recycling of feed nutrients in the available straws of rice and wheat crop can yield an additional 16·31 GJ of energy and 166·97 kg of protein from milk; 81·23 kg of N; 56·00 kg of P₂O₅ and 25·14 kg of K₂O fertilizer from biogas slurry and 1097 kilowatts of power per hectare annually from biogas.     

Introducing greenhouse gas mitigation as a development objective in rice-based agriculture: II. Cost–benefit assessment for different technologies,regions and scales

New tools for land use analysis including detailed cost–benefit assessments are needed to integrate resource management for enhancing farmers’ income and mitigating greenhouse gas (GHG) emissions. The paper comprises an assessment of GHG emissions and economic returns under different mitigation technologies in three rice growing regions in Asia, i.e., Ilocos Norte province (Philippines), Zhejiang province (China) and Haryana state (India). Site-specific data on soil, climate and socio-economics were integrated in the previously developed spreadsheet model TechnoGAS (Technical Coefficient Generator for Mitigation Technologies of Greenhouse Gas Emissions from Agricultural Sectors). Three baseline technologies that differed in terms of inorganic/organic N supply have been compared to different mitigation technologies in form of Marginal Abatement Cost Curves (MACCs). For the baseline technology of inorganic N (urea) fertilization, amendment with phosphogypsum and nitrification inhibitors are the most promising mitigation options resulting in shadow prices of less than US$10 per ton of carbon dioxide equivalent (CE). Assuming a mix of urea and farm yard manure for the baseline, we have tested several options including different irrigation patterns and husk used as fossil fuel. Mid-season drainage had a better cost–benefit ratio (ca. US$20 per t CE) than alternate flooding, but was less profitable than husk utilization (ca. US$4 per t CE). Assuming high organic inputs, biogas technology is, in most cases, the preferable option (ca. US$10 per t CE). Finally, we compiled regional abatement cost curves for selected administrative units using the outcome from regional optimization models. Implementing the three most promising technologies required US$6000 for Dingras municipality, Ilocos Norte, in the Philippines (ca. 10³ ha of rice land potentially providing emission savings of ca. 3000 t CE), US$50,000 for Pujiang county in China (ca. 10⁴ ha providing ca. 27,000 t CE), and US$1.2 million for Karnal district in India (ca. 10⁵ ha providing ca. 220,000 t CE).     

Measuring the costs of African animal trypanosomosis,the potential benefits of control and returns to research

This paper addresses issues surrounding measurement of the potential productivity gains from new livestock technologies and the returns to international livestock research. The approach, applicable to many livestock production constraints and technologies, uses geographic information systems (GIS) to spatially link a biophysical herd simulation model with an economic surplus model. The particular problem examined is trypanosomosis in cattle in Africa, and the potential research product is a multi-component vaccine. The results indicate that the potential benefits of improved trypanosomosis control, in terms of meat and milk productivity alone, are $700 million per year in Africa. The disease now costs livestock producers and consumers an estimated $1340 million annually, without including indirect livestock benefits such as manure and traction. Given an adoption period of 12 years, a maximum adoption rate of 30%, a discount rate of 5%, and a 30% probability of the research being successful within 10 years, the net present value of the vaccine research is estimated to be at least $288 million, with an internal rate of return of 33%, and a benefit/cost ratio of 34:1. ©     

Water use efficiency and economic feasibility of growing rice and wheat with sprinkler irrigation in the Indus Basin of Pakistan

With a population of more than 150 million, Pakistan cannot meet its need for food, if adequate water is not available for crop production. Per capita water availability has decreased from 5600 m³ in 1947 to 1000 m³ in 2004. Water table has gone down by more than 7 m in most parts of the country. Present need is to identify and adopt measures, that will reduce water use and increase crop production. This study was conducted in farmers’ fields during 2002–2004 to evaluate the water use efficiency and economic viability of sprinkler irrigation system for growing rice and wheat crops. Yields and water use were also measured on adjacent fields irrigated by basin flooding, which were planted with the same crop varieties. Sprinkler irrigation of rice produced 18% more yield, while reducing consumption of water to 35% of that used in the traditional irrigation system. Sprinkler irrigation of wheat resulted in a water use efficiency of 5.21 kg of grain per cubic meter of water used compared to 1.38 kg/m³ in the adjacent flooded basins. Benefit–cost analysis showed that adoption of rain-gun sprinkler irrigation for rice and wheat is a financially viable option for farmers. While these findings show large potentials for improving water use efficiency in crop production they also indicate that a large portion of the water applied in traditional flooded basin irrigation is going to groundwater recharge, which has high value near large cities which draw their water from the aquifer.     

Economic evaluation of alley cropping leucaena with Maize-Maize and Maize-Cowpea in Southern Nigeria

Alley cropping is an aspect of agroforestry being developed for small farmers in the tropics. It consists of establishing fast-growing leguminous shrubs or tree species in rows, then controlling the shading from the trees during cropping by pruning the branches which can be used as mulch or green manure to benefit the companion crops planted between the alleys. This paper attempts to assess the economic implications on labour utilization for the management of the leucaena hedgerows, on crop yields and the overall benefits from alley cropping with leucaena. The results show that although the management of leucaena trees increases labour requirements by about 50%, the system can sustain and increase maize yields by over 60%, reduce the use of nitrogenous fertilizers and give an attractive net income and marginal rate of return per unit cost. It gave a reasonable benefit-cost ratio of 1·23 to 1·32 and looks promising, especially for maize production in tropical areas.     

Mapping the total volumetric irrigation water requirements in England and Wales

The net volumetric (m³) irrigation water requirements for the main crop categories currently irrigated in England and Wales have been calculated and mapped within a geographic information system (GIS). The procedure developed by Knox et al. (1996, Agric. Water Manage., 31: 1–15) for maincrop potatoes (Solanum tuberosum) was extended to cater for the other crops currently irrigated. The annual irrigation needs (mm) for the eight major irrigated crop categories, grown on three contrasting soil types at 11 representative weather stations, were determined using a daily water balance irrigation scheduling model. The results were correlated with existing national datasets of climate, current land use, soils and irrigation practice, to generate volumetric (m³) irrigation water requirement maps at 2 km resolution.The total net volumetric irrigation water requirements for a UK ‘design’ dry year (defined as the requirement with a 20% probability of exceedance) are estimated to be 140 × 10⁶ m³ for the eight main crop categories currently irrigated and the 1994 cropping pattern. Previous theoretical dry year demand estimates, using scheduling models and large agroclimatic areas, were 109 × 10⁶ m³ and 222 × 10⁶ m³. The irrigation demand for other crops grown in the open would typically add another 4%.The procedure has been validated nationally, by comparing the calculated dry year demand for 1990 against government irrigation survey returns for 1990, for each crop category, and regionally against National Rivers Authority (NRA) abstraction records for 1990, for each NRA Region. The estimates obtained agree well with the reported distribution between crops and between regions.The most recent actual ‘dry’ year for which comparative data are available is 1990. It is estimated that the dry year requirements for the 1990 land use would have been 148 × 10⁶ m³. Although farmer demand, actual abstractions and crop requirements are not necessarily the same, irrigation survey returns to the Government indicated that 134 × 10⁶ m³ were actually applied, and the NRA estimated from meter returns that 138 × 10⁶ m³ were abstracted. It is noted, however, that some abstraction restrictions were in force, the scope of the data is slightly different and all figures contain inaccuracies. Potential applications for improving irrigation demand management and water conservation at regional and catchment levels are discussed with reference to two contrasting regions.