Nitrogen Efficiency in Mixed Farming Systems

SUMMARY

The problem of nitrogen surpluses in Northwestern Europe is related in part to recent segregation of animal and crop production. A long-term solution can be found by re-integration of the main agricultural production components into mixed farming systems. In a new classification scheme of farming systems, high-input systems are placed in a sequence of modes in agriculture that each address sus-tainability problems in different ways. In this classification scheme, New-Conservation Agriculture (NCA) is considered to be a new mode of farming that aims to replace losses from the system, whilst not overloading it through critical use of non-renewable resources. Mixed farming systems that integrate crops and livestock are a typical example of NCA. The advantageous environmental features of mixed farming systems are illustrated by the favorable nitrogen balance of two experimental prototypes (a conventional and an organic one) where arable, dairy and sheep farming are integrated to a high degree. However, particularly the plowing of grass/clover swards caused serious problems on both farms regarding seedling survival and product quality in sugarbeet, maize, onion, and potato crops. This was due to the occurrence of large pest populations of leatherjackets (Tipula paludosa) and wireworms (Coleoptera: Elateridae).     

Grazing legumes in Europe: a review of their status, management, benefits, research needs and future prospects

In many parts of Europe there has been a net decline in the use of forage legumes since the 1980s, despite the reputed value of legumes for low‐input livestock production systems. The political environment within which livestock farming in much of Europe operates (Common Agricultural Policy) is shifting the balance of economic advantage towards legumes and away from high usage of inorganic fertilizer. This has already been found for legume and grass–legume silages when compared with grass silages with a potential economic gain for farmers averaging 137 € ha^?1, corresponding to an annual benefit for the European livestock farming sector of as much as € 1300 million. Recent literature has shown that legume‐based grazing systems have the ability to reduce environmental problems by increasing the efficiency of N use and by avoiding a high transient surplus of soil mineral N. From the perspective of livestock nutrition, when forage legumes contain moderate levels of secondary compounds, such as condensed tannins and flavonoids, they offer considerable advantages including increased efficiency of N utilization within the digestive tract, reduced incidence of bloat hazard and higher resilience to parasites. Nevertheless, these benefits are partially counterbalanced in both temperate and Mediterranean regions by difficulties in establishment, maintenance and management under grazing. To gain knowledge on mixed grass–legume pastures, further research is required on: (i) the development of sustainable systems of livestock production which can maintain sward persistence and agricultural production under environmental stress; (ii) increasing knowledge of soil–plant–animal relations for a wide range of leguminous species, and under different soil types and climatic situations; and (iii) the benefits for consumers of food produced from low‐input livestock production systems.     

The Economics of Horticultural Biotechnology

Abstract

Technological change has driven economic progress in agriculture and will continue to play a crucial role in die 21st century. The latest wave of technological change in agriculture is based on die ability to specifically modify crop genetics dirough recombinant DNA techniques. Biotech crop varieties have been adopted on a wide scale in some agronomic crops, but horticultural crops face hurdles for commercialization. Market barriers are blocking die production of biotech horticultural crops diat have already been developed. High costs for research, development and regulatory approval combined with the small acreages planted and the diversity of varieties limit die potential for profitable applications of biotechnology for many fruits and vegetables, tree fruits and nuts, and nursery and landscape crops. Like most technological changes in agriculture, die introduction of modern biotechnology has met with spirited political opposition from some quarters. Such opposition could discourage adoption of biotech products that are wanted by some consumers, can be profitable for growers and could reduce the environmental impacts of crop production.     

The Use of Saline Water in Agriculture in the Near East and North Africa Region: Present and Future

SUMMARY

Salinity is a major problem that negatively impacts agricultural activities in many regions in the world, and especially the Near East and North Africa region. Generally, salinity problems increase with increasing salt concentration in irrigation water. Crop growth reduction due to salinity is generally related to the osmotic potential of the root-zone soil solution. This will lead to certain phenological changes and substantial reduction in productivity. Salinity also affects the soil physical properties. Sewage treated wastewater is an alternative water source for irrigation. Using such wastewater will provide a new water resource to expand agricultural activities as well as reduce the environmental pollution. Each country in the region has a unique system of rules and regulations to protect the quality of water resources. Important aspects that should be taken into account when using wastewater for irrigation are discussed, including some information on the different irrigation systems used in the region, and the factors leading to success of using saline water for economic crop production. Information on the use of saline water or marginal saline soils for wheat production and improvement of irrigation systems, including old land irrigation systems, under Egyptian conditions is also presented. The regional experiences and the future prospects of using saline water for crop production that vary greatly among countries in the Near East and North Africa region are summarized. This article also presents information on special cultivation methods, such as protected agriculture and soilless culture that can help in alleviating the salinity effects. Finally, the article includes some examples on the inherited knowledge for saline agriculture that conveys the grower's experience in the Near East and North Africa region where several living examples for unique and sustainable cultivation system are still in operation. One of the most impressive cultivation techniques for bio-saline crop management in Egypt is the Edkawy production system.     

Forage quality of leaf fodder from the main woody species in Iceland and its potential use for livestock in the past and present

Woody species played, and in many Nordic regions still play, a very important role in livestock feeding. However, forage quality (contents of macroelements and fibre fractions) of the leaves of common woody species is often inadequate. The aim of our study was to determine forage quality of leaves of Betula nana, Betula pubescens, Salix lanata, Salix phylicifolia and Sorbus aucuparia from Iceland and to compare it with the forage quality of the common native grass Deschampsia cespitosa and the introduced grass Alopecurus pratensis used by contemporary Icelandic farmers for forage production. Samples were collected at four localities in Iceland in late June 2013 and analysed for nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), neutral and acid‐detergent fibre and lignin concentration. Analyses were compared with the optimum range for cattle and sheep nutrition. The nutritive value of leaves of the Icelandic woody species was relatively high, and analysis showed their nutritive content satisfied both cattle and sheep nutrient requirements for N, P, K, Ca and Mg, but the relatively high content of indigestible lignin in all woody species could cause problems for livestock metabolism. Grasses were characterized by lower P, Ca and Mg, but substantially higher K concentrations, and higher N:P and K:(Mg + Ca) ratios. The forage quality of leaves of woody species increased in the order B. nana < B. pubescens < S. phylicifolia < S. aucuparia < S. lanata. Results are discussed in relation to use of leaf fodder in the past, when woody species, particularly Salix spp., are likely to have played an important role in livestock feeding.     

Redesigning Industrial Agroecosystems

Summary

The development and mixed benefits of high-input industrial agriculture are reviewed, then illustrated with findings from a Georgia landscape study. As a basis for considering ways to reduce the serious negative aspects of industrial agriculture, we compared the basic ecological energetics and processes of natural ecosystems with pre-industrial, industrial, and reduced-input conservation tillage agroecosystems. We also reviewed our 20-year comparison of conventional tillage with no-till systems. The conclusion is that current trends to redesign industrial agriculture along the lines of reduced-input conservation tillage systems should be accelerated in order to maintain and restore soil quality, and to reduce pollution and soil erosion at the landscape scale.     

Forage Legumes for Sustainable Cropping Systems

SUMMARY

Perennial and annual forage legumes are important components of sustainable cropping systems. Forage legumes are a primary source of forage to supply protein and fiber for livestock rations. They can be grazed, or stored as hay or silage. They contribute biologically fixed N and sustain the soil by reducing erosion and increasing soil organic matter levels. Diversifying cropping systems by including legumes can also reduce weed, insect, and disease incidence. Potential new uses of legumes include phytoremediation of N contaminated sites and capturing N lost from cropping systems. Legumes also have potential use as a feedstock for renewable energy production. Legumes have traditionally been used in rotation with grain crops but more recently have been shown promise as winter cover crops, intercrops with grain crops, and as living mulches. In this review, we discuss traditional and new roles of forage legumes in sustainable cropping systems with examples primarily chosen from northern USA and Canada.     

Nutritional and Economic Benefits of Enhanced Vegetable Production and Consumption

SUMMARY

Vegetables are a major source of dietary micronutrients, but abiotic and biotic constraints limit vegetable production and consumption in Asia. Per capita vegetable consumption in Asia is far below the required level to satisfy the recommended dietary micronutrient intakes. Empirical evidence and discussion in this article show that enhanced vegetable production and consumption in Asia can play a catalytic role in the overall economic development by improving the nutritional status, learning capabilities and managerial capacities of farmers, generating incomes and jobs in both the farm and non-farm sectors, and improving resource use efficiency in agriculture. Rapid urbanization, higher incomes, and greater awareness amongst consumers and producers to diversify their food and production systems have increased the demand for vegetables in Asia. To realize this potential demand, especially during the off-season of vegetable production, trade-oriented and production enhancement strategies are suggested in this article. The trade-oriented policies can help link the favorable vegetable producing areas with consumption centers, and production oriented policies can overcome the biotic and abiotic constraints of vegetable production by developing economically viable, socially acceptable, and environmentally friendly technologies. Both the strategies require government support and increased allocation of research funds and manpower for vegetable cultivation. Government policies to stabilize vegetable production and trade, can mitigate the risk inherit in vegetable production.     

Die Rolle der Ertragssteigerung im Anpassungsprozess der Landwirtschaft

Measures undertaken in the Federal Republic of Germany to rationalize agricultural production, viz. a reduction of intensive farming, simplification of farm production methods, and the introduction of specialization and mechanization, have been carried to their near completion in modern agricultural holdings. It is now necessary to introduce a new overriding economic principle if we are to successfully meet further wage increases and price reductions and improve the income level of the agricultural population. A new farm management concept based on the idea of a radical increase in specific intensive production methods is now being developed. In view of the high fixed costs in West German agriculture, the degression of fixed costs per production unit outweights the progression of variable costs when output is increased. In other words, higher yields per hectare and animal effect a decrease in unit costs. Nitrogen fertilizer being the most important factor in output increase, its profitable level is examined by means of six marginal value analyses. The fertilizer optimum is reached when marginal costs and marginal yields balance each other out. In all six examples this optimum coincides almost exactly with the point of maximum yield per hectare. This simplifies the problem considerably, at least under the conditions established for six examples. The optimal input level of nitrogen fertilizer does not have to be determined by means of a complicated marginal value analysis. It lies just under the maximum yield per hectare. We cannot expect that price-cost alterations will push this fertilizer optimum up within the near future. However, we may assume that new possibilities will open up for nitrogen fertilizer. In the first place, the majority of the agricultural holdings are still a long way from having reached the fertilizer optimum now economically feasible. Secondly, the present level of fertilizer optimum is constantly being raised as the result of technological advances. It is the task of economic counselling to achieve the fullexploitation of available earning power resources and the task of scientific research todevelop new earning power resources. The exploitation and the development of earning power resources can have very positive results in the case of inorganic fertilizer, since through its application it is possible to even out income disparities in agriculture

—help small holdings in particular, mineral fertilizer being a divisible input factor

—come closer to a solution of the central probrem of the agriculture of the Federal

—Republic of germany, that of combining high labour productivity with high soil productivity.

     

Socioeconomic and Agricultural Factors Associated with Mixed Cropping Systems in Small Farms of Southwestern Guatemala

SUMMARY

Many small farming communities in Latin America have modified their traditional cropping systems to incorporate non-traditional export crops (NTEC). The shift from subsistence to commercial agriculture is perceived by development agencies as an opportunity to alleviate poverty in rural areas. However, most small-scale farmers are not familiar with the production problems of NTEC, such as Bemisia tabaci and various geminiviruses transmitted by this whitefly species. In the absence of adequate technical assistance, due to drastic budgetary reductions in national agricultural research programs, farmers have relied on agrochemicals to protect their NTEC. This situation has led to considerable pesticide abuse and rejection of contaminated produce in international markets. This study analyzes some of the factors determining the adoption of NTEC and displacement of traditional food crops in southwestern Guatemala, and suggests possible measures to allow small farming communities to benefit from broad-based cropping systems that include both traditional and non-traditional food and cash crops.     

A Risk Management Perspective on Integrated Weed Management

Abstract

The variability inherent in agriculture influences many crop production decisions made by farmers, including weed management. This paper addresses how farmers perceive the variability, or risk, associated with integrated weed management systems in terms of yield, economic returns, and time and labor management. This paper addresses how key biological time constraints such as periodicity of weed emergence, rate of crop growth and development, and critical periods of weed control can influence the outcome of integrated weed management systems. A key component to developing successful integrated weed management systems lies in the ability of the crop producer to align individual time and labor management issues with existing biological time constraints.     

Weed problems of the next decade in Britain

The potential changes in weed problems in British agriculture and horticulture over the next decade are reviewed. The attributes which confer survival and success to weed species are considered, of which the most important for arable weeds is seed behaviour. These attributes are then discussed in relation to the changes which are deemed likely to occur in various cropping systems. In arable land, the main factors influencing weed population composition are method of straw disposal, level of cultivation, season of drilling, crop grown, fertilizer regime, herbicide usage and herbicide resistance. Few major changes in agriculture are foreseen, but there will be a trend towards increasing specialization in many areas. The predominance of winter cereals and oilseed rape will continue, which will favour autumn-generating weeds such as Galium aparine and Alopecurus myosuroides. It is postulated that most weed problems over the next decade will arise from existing weeds or from native plants common in field margins from which they could invade fields through changes in management. A few new aliens, especially grasses, may well appear, e.g. Phalaris paradoxa. Weeds could also arise from recently introduced crop plants, e.g. Bromus willdenowii and B.carinatus, which may present problems in the future, just as cereal volunteers are often a problem at present.     

The Importance of Biodiversity in Agroecosystems

SUMMARY

This article identifies the important functions and benefits of biodiversity in agriculture, for sustainable crop production and food security. After clarifying impacts from the decline of biodiversity in agriculture, the article summarizes principles, practices and policies for biodiversity conservation and enhancement in farming systems and in landscapes. Some of the strategies identified build upon valuable local experiences and knowledge in traditional farming practices, while others take advantage of recent scientific findings in agroecology and ecosystem health. The analysis suggests the value of adopting an agroeco-systems approach, beyond a focus on genetic resource conservation alone-to implement other biodiversity-enhancing methods in farms, such as integrated ecological pest and soil management. Attention is also given to the challenges by conflicting agricultural policies that contribute to the decline of biodiversity in farming systems, and potential of reforming such policies. The practices and approaches reviewed in this analysis show effective ways to link biodiversity conservation and sustainable agriculture.     

Research Priorities in Natural Systems Agriculture

SUMMARY

Over the course of millennia and most dramatically in recent years, agriculture has eroded natural capital as it has supplied human demands. These tendencies can be offset by infusions of fossil fuels for fertility, pest control and traction, but only partially and not over the long term. This could be called the “problem of agriculture,” in contrast to problems in agriculture. Natural ecosystems are unmatched for efficient nutrient recycling, solar energy use, and biodiversity preservation, but they cannot feed dense human populations. An ecological agriculture that is a synthesis of natural and agricultural systems can save soils from erosion and reduce chemical and water use. Reducing chemical pollution of air, water and soils will conserve wildlife habitat, improve water quantity and quality and protect human health. By practicing an agriculture that has conservation as a direct result, farmers can become better stewards of the land. Lower input costs and inherent sustained soil fertility will mean more profit for farmers and communities. Principles of natural systems agriculture (NSA) are applicable to any food- or fiber-production system worldwide. In the central Great Plains of the United States, agriculture should mimic the native prairie, which is a polyculture of herbaceous perennial plants. The Land Institute has spent 25 years studying the structure and function of prairies. Now we and other research organizations are breeding perennial grain crops, including cool- and warm-season grasses, legumes, and composites. We are following two parallel strategies: selecting wild perennials for greater seed production and other traits of domestication and hybridizing wild perennials with annual crops to combine desired traits. Although the breeding process will take many years, the effort will be repaid many times over if we achieve our goal: a lasting solution to the 10,000-year-old problem of agriculture.     

The Role of Nutrient-Efficient Crops in Modern Agriculture

Summary

Nutrient-efficient crops have an important role in modern agriculture. In the low-input systems that characterize most of world agriculture, nutrient-efficient crops improve crop productivity. In high-input systems of the developed world, nutrient-efficient crops are valuable in reducing pollution of surface and ground water resources from intense fertilization. Recent developments in molecular biology, root biology, rhizosphere interactions, and modeling present new opportunities for the understanding and improvement of crop nutrient efficiency. The degree and extent of nutritional limitations to crop productivity, and the economic and ecological liabilities of intensive fertilization, are such that eventually nutrient-efficient crops will be an important part of integrated nutrient management of cropping systems.     

Conceptual Framework for Evaluating Sustainable Agriculture

SUMMARY

Evaluation of outcomes is arguably one of the most critical and challenging tasks of research and education programs in agriculture. Assessing research and education in sustainable agriculture is particularly complex because of the need to assess interactive social, environmental, and economic factors within farming systems. Definitions and indicators of sustainability vary widely among practitioners, and indirect and non-tangible factors are difficult to measure. No single evaluation model has been found to serve as an adequate tool for assessing investments in sustainable agriculture. This article describes challenges and issues in sustainable agriculture evaluation and proposes the incorporation of elements of two frameworks: the Program Evaluation (Bennett's Hierarchy) and the Driving Force-State-Response (DSR) models. These models help organize indicators and facilitate evaluation in light of the complexity of sustainability.     

Making Rice a Perfect Food

Abstract

Despite a significant increase in food production during the last century, world production will need to be doubled or tripled by the year 2050 to meet the needs of an expected 10 billion global population. Fortunately, a second revolution in agriculture appears to be taking place from advances in biotechnology. Worldwide in 1999, about 40 million hectares of transgenic plants were grown, and this area is expected to increase significantly for years to come. Rice (Oryza sauva L.) is the staple food of the majority of 3.5 billion people in Asia. Increases in population in the rice growing regions of Asia will require 70% more rice in 2025 than is consumed today. In addition, rice, in its milled form, is poor in essential amino acids and a range of vitamins and micronutri-ents, which creates malnutrition. With the increasing number of genes discovered in plants and other organisms, transgenic research is being utilized to improve agronomic traits of rice, such as resistance to biotic and abiotic stress, and to increase photosynthetic efficiency which collectively increase yield. Research is also moving toward improvement of grain quality traits, including amino acids, micronutrients, and vitamins. Genome sequencing and the techniques for rice transformation have been developed. Thus, collaborative efforts in genomics, transformation, and molecular breeding of rice are expected to lead to a significant contribution to global food security. In this article, we review the current status of genetic improvement of rice. Improved methods for transgene expression in rice and potential modifications that will significantly improve yield and grain quality of rice are also discussed.     

Manipulation of herbage production by altering the pattern of applying nitrogen fertilizer

The redistribution of herbage production during the growing season to synchronize herbage supply with feed demand by livestock by altering the application pattern of a range of nitrogen (N) fertilizer rates was studied. Application rates of N were 50, 150 and 250 kg N ha^?1 per annum and patterns were with 0·60 of N fertilizer applied before June (treatment RN) and with only 0·20 of N fertilizer before June (treatment IN). Treatments were imposed in a cutting (simulated grazing) experiment (Experiment 1), which was conducted for 2 years and a grazing experiment (Experiment 2) which was conducted for 3 years. In both experiments, herbage production was reduced in April and May and increased in the June–October period on treatment IN relative to RN, but annual herbage production was not significantly affected except in the third year of Experiment 2, when treatment RN had significantly (P < 0·05) higher herbage production than treatment IN. Crude protein (CP) concentration of herbage was lower in April and May on treatment IN than treatment RN. However, CP concentration of herbage was rarely below 150 g kg^?1 DM and so it is unlikely that livestock productivity would be compromised. On treatment IN, concentrations of CP in herbage were higher in the late summer than on treatment RN, which may increase livestock productivity during July and August when livestock productivity is often lower. Altering the strategy of application of N fertilizer did not affect in vitro dry matter digestibility of herbage.     

Hay production from lowland semi-natural grasslands: a review of implications for ruminant livestock systems

Data on total, seasonal and between-year variability in the productivity and nutritional quality of cut forages obtained from a range of lowland semi-natural grasslands are reviewed. Dry-matter production, as hay, from unfertilized species-rich semi-natural grasslands ranged from less than 20% to about 80% of the production that might be expected from agriculturally improved and intensively managed grasslands. Unfertilized species-rich grasslands had lower growth rates, reflecting low nutrient availability in spring and early summer. Low soil phosphorus availability appears to be a key factor allowing high species-richness to be maintained. The in vitro digestibilities of herbage cut for hay from semi-natural grasslands were 20%, or more, below values for conserved forages from intensively managed grassland. When losses incurred during the hay-making process were taken into account, then the nitrogen content of hays from many semi-natural grasslands appear to be sub-optimal for productive livestock. Metabolizable energy values of herbage cut for hay were 10–40% below values for intensively managed conserved grass. Phosphorus content of forages from most species-rich grasslands was either below the metabolic requirement of livestock or inadequate to sustain high individual animal performance. Potential problems associated with supplementation of the diet with phosphorus, and with high calcium-to-phosphorus ratios, are discussed. Although potassium content of most of the herbage cut for hay was adequate for productive ruminant livestock, exceptions arise with hay cut after July. The magnesium content of cut herbage from some semi-natural grasslands was below an adequate level for productive livestock. Most cut herbage appeared to contain adequate amounts of sodium. Inadequacy of the mineral content of hays from semi-natural grasslands for ruminant livestock will be exacerbated by nutrient losses incurred during the hay-making process and particularly so when hay- making is prolonged by wet weather. Few feeding studies using hays from semi-natural grasslands of high nature conservation interest have been conducted. Lack of such data makes it difficult to plan any integrated use of these hays in ruminant feed budgets for livestock systems.     

Pasture legumes differ in herbage production and quality throughout spring,impacting their potential role in fodder conservation and animal production

This study reports on the herbage production and quality of a range of pasture legume species during spring, at three sites with moderate to strongly acidic soils in southern NSW, Australia. These data have enabled prediction of livestock production when legumes are conserved as silage or hay. Total herbage production, its timing and quality differed significantly between species, which generally was not predicted by the traditional metric of time to flowering. Trifolium incarnatum L., T. michelianum L., Biserrula pelecinus L., Ornithopus sativus Brot. and Hedysarum coronarium L. all maintained growth rates exceeding 200 kg DM/ha/d for 4 weeks over spring, while T. vesiculosum Savi. maintained this for 6 weeks, with a peak growth rate of 561 kg DM/ha/d. Herbage quality of all species declined over time and was greatest in species with a rapid increase in stem‐to‐leaf ratio or with weak stems, resulting in lodging. The modelling inferred that maximizing potential livestock production via fodder conservation required earlier cutting. Only the indeterminate species B. pelecinus and Ornithopus spp. increased potential liveweight gain per hectare through delayed harvesting from (probable) silage to hay‐making time.