Intensive Agricultural Production Systems Research Articles

Using an Uptake Enhancer to Mitigate Nitrogen Leaching While Enhancing Uptake Efficiency

Nitrogen (N) has the most crucial influence on raising agricultural productivity of all other plant nutrients given to crops. However, 50% of the N given to crops is dissipated to the environment globally, resulting in environmental concerns due to leaching. Current research shows that intensive agricultural production systems, which are still used in a large proportion around the world, are prone to N loss. This study aimed to investigate the effect of uptake enhancer applications on N movement in the soil profile based on 10 cm depth intervals, as well as its effects on N uptake and vegetative growth of oats at 4-week intervals over a 16-week period, using sandy soil as a growing medium. Oats were cultivated in a glasshouse setting in polyvinyl chloride (PVC) columns of 60 cm in height. Six treatments were employed at the 3rd leaf growth stage, and each was replicated four times. The experiment had a constructive and a destructive part, which was employed to monitor crop N uptake at four growth stages. Analyses of soil and plant samples were carried out in all the growth stages. The treatments containing the uptake enhancer prevented N from leaching, particularly at the top 20 cm soil depth, with impressive reductions of 194% at 0–10 cm depth and 186% at 10–20 cm depth, during the first 4 weeks after planting. The uptake enhancer also promoted early vegetative growth and crop performance with 15%. In conclusion, the study revealed that employing the uptake enhancer can improve the efficacy of N fertilizer, thereby reducing the application rate of the fertilizer in agroecosystems.

Exploring the Potential of Biostimulants to Optimize Lettuce Cultivation in Coupled and Decoupled Aquaponics Systems: Growth Performance, Functional Characteristics and Metabolomic Analysis

Zero-discharge and low-input aquaponics systems are a promising alternative to the intensive agricultural and aquacultural production systems currently used, ensuring high environmental sustainability. However, new approaches and management practices are needed to increase their productivity to reach the yields of classic production systems. In this context, the present study investigated for the first time the potential of two biostimulants to improve lettuce performance in aquaponics, whether coupled or decoupled, with hydroponics serving as a control. A comprehensive evaluation was conducted to assess the plant functional (focusing on the photosynthetic process evaluation) and growth responses at the whole-plant level. In addition, the nutritional state of the leaves was determined and metabolomic analysis was performed at the cellular level, the latter also for the first time in aquaponics research. The results demonstrated the limitations that coupled aquaponics poses in relation to lettuce growth, function and metabolism, which were already obvious from the 12th day of the experiment. Indicatively, the plants grown under coupled aquaponics exhibited a notable decrease in the leaf fresh weight, potassium content and nitrogen content, with reductions of 80%, 60%, and 30%, respectively, in comparison to the hydroponics control. However, the combined physiological and metabolomic data indicate that these plants down-regulate processes and metabolism to acclimate to low nutrient levels in lettuce leaves rather than experiencing damage. The application of biostimulants did not significantly optimize the plants’ performance, though one of them appeared to be effective in improving some aspects of the photochemical efficiency. The decoupled and hydroponics systems resulted in similarly high yields and efficiency in terms of plant function, without any marked contribution from the biostimulants. We conclude that the decoupled aquaponics system has been successful in achieving yields comparable to those of hydroponics, with lower chemical inputs. Future studies should focus on examining other biostimulants in this system to further improve its performance while maintaining its environmental benefits within a circular economy framework.

Control of the concentration of the macroelement phosphorus in the substrate when growing tomatoes in protected soil conditions

Although most tomatoes are grown in open ground, their cultivation in glass greenhouses or tunnel-typegreenhouses covered with plastic film is becoming more common to supply local markets with fresh fruit. In closed soil, mainly tall varieties of tomatoes are grown. They make it possible to use the area of greenhouses as efficiently as possible and get rich harvests. Tomatoes grown in greenhouses can be stored for 11 months, unlike those grown in open ground. Tomatoes are usually harvested unripe and ripen during transportation or on store shelves. Different types of tomatoes grown in greenhouses tend to have a longer shelf life, better taste and higher market value than those grown in the open field. Usually, plants are attached to the supports with a single wire, while the extra side shoots (stepchildren) are removed so that only one stem remains. The height of the tomato bushes can be gradually reduced for convenience immediately after the ripening of the first bunches of tomatoes. Shoots and inflorescences are removed to increase the length of the tomato bush, the number of fruits on it and their weight in order to meet the needs of the market. Taste, color, shape and texture are extremely important criteria for evaluating the quality of fresh tomatoes. Also, the fruits must be clean and contain no signs of decay or disease. Fresh tomatoes should be uniform in shape, symmetry and size. They should have a bright and uniform color, not contain green shoulders, spots and characteristic signs of immaturity. High concentrations of carbon dioxide (600–1000 ppm) are maintained in greenhouses to improve the process of photosynthesis, growth rate and yield. This practice is very common in low yield regions and intensive agricultural production systems. Although planting tomatoes in soil in tunnel-type greenhouses is still quite common, most intensive-type green-house tomato varieties are grown on substrates such as mineral wool. Fertigation provides adequate nutrient supply and eliminates most of the factors associated with heavy soil characteristics that are difficult to control. Growing tomatoes in greenhouses requires the use of a significant amount of water. To feed tomatoes, their producers also need to take into account the mass and degree of solubility of mineral fertilizers in water. Some elements or compounds present in irrigation water can affect the growth of plants, which is why there is a need to control their level. The paper investigates the influence of the concentration of the macroelement phosphorus in the mineral wool substrate on the growth and development of the Rosaletta (pink) tomato crop during the period of mass fruiting in protected soil conditions. It was established that the photoelectrocolorimetric method for determining the phosphorus content in mineral wool hoods is quite sensitive, simple and recommended for use in serial analyses. The determined average value of the phosphorus macroelement content (50.0 mg/l) turned out to be higher than that required for growing tomatoes in the period of mass fruiting. Controlling the phosphorus content allows you to significantly prevent tomato diseases and obtain high-quality crops.

A genomic perspective on South American human history

It has generally been accepted that the current indigenous peoples of the Americas are derived from ancestors from northeastern Asia. The latter were believed to have spread into the American continent by the end of the Last Glacial Maximum. In this sense, a joint and in-depth study of the earliest settlement of East Asia and the Americas is required to elucidate these events accurately. The first Americans underwent an adaptation process to the Americas’ vast environmental diversity, mediated by biological and cultural evolution and niche construction, resulting in enormous cultural diversity, a wealth of domesticated species, and extensive landscape modifications. Afterward, in the Late Holocene, the advent of intensive agricultural food production systems, sedentism, and climate change significantly reshaped genetic and cultural diversity across the continent, particularly in the Andes and Amazonia. Furthermore, starting around the end of the 15th century, European colonization resulted in massive extermination of indigenous peoples and extensive admixture. Thus, the present review aims to create a comprehensive picture of the main events involved in the formation of contemporary South American indigenous populations and the dynamics responsible for shaping their genetic diversity by integrating current genetic data with evidence from archeology, linguistics and other disciplines.

Landscape Integrated Soil and Water Conservation (LISWC) System for Sloping Landscapes in Atlantic Canada

Soil and water are fundamental and precious resources for agriculture. In Atlantic Canada (AC), intensive agricultural production systems have led to detrimental environmental effects such as soil erosion and the contamination of receiving waters, posing significant threats to the resilience and sustainability of the agro-ecosystem. Although many beneficial management practices (BMPs) have been developed, they all have their shortcomings and there are often trade-offs for each individual BMP. In this paper, a new paradigm is proposed for soil and water conservation—landscape integrated soil and water conservation (LISWC), a system designed to conserve and reuse soil and water within the landscape by integrating multiple BMPs based on an understanding of the landscape processes and knowledge about the BMPs. On a typical sloping field in AC, an LISWC system can be established by integrating BMPs such as diversion terraces and grassed waterways, tile drainage, water retention structures, supplemental irrigation, conservative tillage practices and soil–landscape restoration. Each individual BMP is designed to enhance one aspect of soil and water conservation but working on their own, they are all insufficient for the landscape as a whole and sometimes even have negative impacts. However, once integrated in the landscape, they complement each other: water erosion is reduced by diversion terraces and grassed waterway and conservative tillage, field drainage condition is enhanced by tile drainage, runoff and tile drained water is stored in the retention structure and reused for irrigation, and most eroded soil is returned to the soil loss area with soil–landscape restoration. This holistic landscape perspective can be used to develop LISWC systems for other landform types or applied at watershed or regional scales. Future studies are needed for the connections and interactions between individual BMPs, and analysis on the overall economic benefit of an LISWC system.

Farmer's behaviors toward pesticides use: insight from a field study in Oriental Morocco.

Pesticides are a vital component of modern agriculture. So, these chemical compounds could play a crucial role in maintaining high agricultural productivity. However, high-input intensive agricultural production systems in which more effective and widespread use of pesticides could harm human health and the environment. As we know, most of the farmers in developing countries used pesticides without taking the necessary precautions. The present study aims to assess farmers’ knowledge and understand the pattern of use of pesticides in Oriental Morocco. We based our approach on a standardized questionnaire with 140 farmers to evaluate their knowledge, attitude, and awareness about the pictograms used on pesticide labels. The results show that the farmer had a low level of education; only 14% were in university. More than 65% overuse pesticides and 60% did not respect the pre-harvest interval. Many farmers did not know the standard pictograms used on pesticide labels, 90% acknowledged only the crossbones and the fire sign, and 33% gave false interpretation or misunderstood these pictograms. These results show that the farmers in Eastern Morocco seem to be ignorant of pesticide danger and lack of safety education. They have no idea how to deal with the pictogram on the pesticide label. Pesticide safety education is necessary to induce protective behavior among farmers and prevent the residue of pesticides in foodstuff. The comprehension of pictograms on pesticide labels is crucial to reduce the risk of poisoning.

Exposure to pesticides, their incarnation during pregnancy and their effect on the neurodevelopment of infants, children of mothers of families residing in coffee growing areas: Cohort study, in southwest Antioquia

Background: The intensive agro-industry of coffee, with consumption of pesticides has ordered the course of life of men and women residents of municipalities in the territories of the Southwest Antioquia; Colombia. Colombia has a social processes of incarnation of pesticides that differ from other countries, with influence on neurodevelopment, unknown to date.Aim: To study the relationship between different pathways and patterns of incarnation of exposure to OP pesticides during pregnancy, and peripheral cholinesterase levels, with neurodevelopmental profiles in their infants inhabitants of eight (8) municipalities with conventional coffee growing systems.Methods: Prospective cohort and population base of 200 women. Data obtained through a survey during pregnancy. As biomarker of pesticide incarnation, erythrocyte acetylcholinesterase-AChE and serum butyrylcholinesterase-BChS were determined in three blood samples in the three trimesters of pregnancy The clinical and anthropometric data were obtained from the medical records, interviews and direct measurements of pregnant women and their children. Neurodevelopment was assessed in months 3 and 4 of postnatal life applying the neurodevelopmental scales of Bayley-IIIResults: Pregnant women who live in agro-farmer municipalities embody exposure to pesticides mainly because of their close ties not only to work but also to daily intensive agricultural production systems, a link that begins for most of them with their ancestors and could continue with their children. The trajectory of AChE during pregnancy described an ascending pattern throughout the trimesters of pregnancy and was not affected by the pathways of incarnation of pesticide exposure. On the contrary, the trajectory of the BChS during pregnancy described a downward trend throughout the quarters of pregnancy and was modified by the pathways of incarnation of pesticide exposure.In the development of neurodevelopment, a decrease in the fine motor domain score was related to exposure to pesticides in pregnant women.

Assessing the efficiency and sustainability of wheat production systems in different climate zones in China using emergy analysis

China is the country with the largest wheat planting area in the world, and wheat is one of the two main staple food crops consumed in China. Wheat is widely cultivated in 15 provinces throughout the country and across 3 climate zones including the subtropical monsoon climate zone, temperate monsoon climate zone and temperate continental climate zone. The natural conditions of each climate zone are different, and the ways in which the wheat production system operates are different. To ultimately safeguard the production and explore the similarities and differences in input and output of the same system under different climate conditions, the emergy method was used to research the comprehensive performance of the wheat production system based on 2014 statistical data from China. The results indicate that there was a significant variance in the input of local renewable environmental resources, ranging from 0.48E+14 sej/ha in Xinjiang in the temperate continental climate zone to 4.46E+14 sej/ha in Shaanxi in the temperate monsoon climate zone. Among the three climatic zones, the temperate continental climate zone had the lowest emergy self-support ratio (0.13), followed by the temperate monsoon climate zone (0.15) and then the subtropical monsoon climate zone (0.20). Regions in which natural resources are insufficient, such as temperate continental climate zone, need additional purchased resources to maintain normal operation of the wheat production system. Compared with other intensive agricultural production systems, the wheat production system is extensive and low-cost and has room for improvement with more artificial input. The Middle-Lower Yangtze River Plain at the junction of temperate monsoon climate zone and subtropical monsoon climate zone is the most efficient region for planting wheat based on the ratio of the entire emergy input to the entire energy output. This ratio should be considered in the adjustment of the agricultural cropping structure to make use of resources more effectively.

Determining Reference Evapotranspiration in Greenhouses from External Climate

AbstractEstimations of Penman-Monteith reference evapotranspiration (EToPM) in greenhouses can benefit the operation of these intensive agricultural production systems. Meteorological variables req...

The trouble with cover crops: Farmers’ experiences with overcoming barriers to adoption

AbstractCover crops are known to promote many aspects of soil and water quality, yet estimates find that in 2012 only 2.3% of the total agricultural lands in the Midwestern USA were using cover crops. Focus groups were conducted across the Corn Belt state of Iowa to better understand how farmers confront barriers to cover crop adoption in highly intensive agricultural production systems. Although much prior research has focused on analyzing factors that help predict cover crop use on farms, there is limited research on how farmers navigate and overcome field-level (e.g. proper planting of a cover crop) and structural barriers (e.g. market forces) associated with the use of cover crops. The results from the analysis of these conversations suggest that there is a complex dialectical relationship between farmers' individual management decisions and the broader agricultural context in the region that constrains their decisions. Farmers in these focus groups shared how they navigate complex management decisions within a generally homogenized agricultural and economic landscape that makes cover crop integration challenging. Many who joined the focus groups have found ways to overcome barriers and successfully integrate cover crops into their cropping systems. This is illustrated through farmers' descriptions of their ‘whole system’ approach to cover crops management, where they described how they prioritize the success of their cover crops by focusing on multiple aspects of management, including changes they have made to nutrient application and modifications to equipment. These producers also engage with farmer networks to gain strategies for overcoming management challenges associated with cover crops. Although many participants had successfully planted cover crops, they tended to believe that greater economic incentives and/or more diverse crop and livestock markets would be needed to spur more widespread adoption of the practice. Our results further illustrate how structural and field-level barriers constrain individual actions, as it is not simply the basic agronomic considerations (such as seeding and terminating cover crops) that pose a challenge to their use, but also the broader economic and market drivers that exist in agriculturally intensive systems. Our study provides evidence that reducing structural barriers to adoption may be necessary to increase the use of this conservation practice to reduce environmental impacts associated with intensive agricultural production.

Estimating soil carbon dynamics in intercrop and sole crop agroecosystems using the Century model

AbstractUsing process‐based models to predict changes in carbon (C) stocks enhances our knowledge on the long‐term dynamics of soil organic carbon (SOC) in various land management systems. The objective of this study was to apply the Century model to evaluate temporal SOC dynamics in two temperate intercrop systems [1:2 (one row of maize and two rows of soybeans); 2:3 intercrop (two rows of maize and three rows of soybean)] and in a maize and soybean sole crop. Upon initiation of intercropping, SOC increased by 47% after ≈ 100 years, whereas SOC in the maize sole crop increased by 21% and 2% in the soybean sole crop. The quantity of crop residue input was sufficient to increase the active (turnover time of months to years) SOC fraction in the intercrops and the maize sole crop, but not in the soybean sole crop. The slow fraction, with a turnover time of 20 to 50 years, increased in all crop systems and was the major driver of SOC accumulation. A 3 to 15% loss of SOC from the passive fraction, with a turnover time of 400 to 2000 years, in all crop systems showed the long‐term impact of land‐use conversion from historically undisturbed native grasslands to intensive agricultural production systems. This study provided an example of the potential of process‐based models like Century to illustrate possible effects of cereal–legume intercropping on SOC dynamics and that the model was able to predict SOC stocks within –7 to +4% of measured values. We conclude, however that further fine‐tuning of the model for application to cereal–legume intercrop systems is required in order to strengthen the relationship between measured and simulated values.

Systems biology and genome-wide approaches to unveil the molecular players involved in the pre-germinative metabolism: implications on seed technology traits.

The pre-germinative metabolism is among the most fascinating aspects of seed biology. The early seed germination phase, or pre-germination, is characterized by rapid water uptake (imbibition), which directs a series of dynamic biochemical events. Among those are enzyme activation, DNA damage and repair, and use of reserve storage compounds, such as lipids, carbohydrates and proteins. Industrial seedling production and intensive agricultural production systems require seed stocks with high rate of synchronized germination and low dormancy. Consequently, seed dormancy, a quantitative trait related to the activation of the pre-germinative metabolism, is probably the most studied seed trait in model species and crops. Single omics, systems biology, QTLs and GWAS mapping approaches have unveiled a list of molecules and regulatory mechanisms acting at transcriptional, post-transcriptional and post-translational levels. Most of the identified candidate genes encode for regulatory proteins targeting ROS, phytohormone and primary metabolisms, corroborating the data obtained from simple molecular biology approaches. Emerging evidences show that epigenetic regulation plays a crucial role in the regulation of these mentioned processes, constituting a still unexploited strategy to modulate seed traits. The present review will provide an up-date of the current knowledge on seed pre-germinative metabolism, gathering the most relevant results from physiological, genetics, and omics studies conducted in model and crop plants. The effects exerted by the biotic and abiotic stresses and priming are also addressed. The possible implications derived from the modulation of pre-germinative metabolism will be discussed from the point of view of seed quality and technology.

Pesticide runoff from energy crops: A threat to aquatic invertebrates?

The European Union aims to reach a 10% share of biofuels in the transport sector by 2020. The major burden is most likely to fall on already established annual energy crops such as rapeseed and cereals for the production of biodiesel and bioethanol, respectively. Annual energy crops are typically cultivated in intensive agricultural production systems, which require the application of pesticides. Agricultural pesticides can have adverse effects on aquatic invertebrates in adjacent streams. We assessed the relative ecological risk to aquatic invertebrates associated with the chemical pest management from six energy crops (maize, potato, sugar beet, winter barley, winter rapeseed, and winter wheat) as well as from mixed cultivation scenarios.The pesticide exposure related to energy crops and cultivation scenarios was estimated as surface runoff for 253 small stream sites in Central Germany using a GIS-based runoff potential model. The ecological risk for aquatic invertebrates, an important organism group for the functioning of stream ecosystems, was assessed using acute toxicity data (48-h LC50 values) of the crustacean Daphnia magna. We calculated the Ecological Risk from potential Pesticide Runoff (ERPR) for all three main groups of pesticides (herbicides, fungicides, and insecticides). Our findings suggest that the crops potato, sugar beet, and rapeseed pose a higher ecological risk to aquatic invertebrates than maize, barley, and wheat. As maize had by far the lowest ERPR values, from the perspective of pesticide pollution, its cultivation as substrate for the production of the gaseous biofuel biomethane may be preferable compared to the production of, for example, biodiesel from rapeseed.

On-farm assessment of soil erosion and non-point source pollution in a rain-fed vegetable production system at Dianchi lake’s catchment, southwestern China

Vegetable is important cash crop in Dianchi lake’s catchment, but the non-point source (NPS) pollution from the intensive agricultural production systems is a critical hurdle on the alleviation of serious eutrophication in Dianchi lake. Our objectives were to quantify soil erosion and NPS pollution in rain-fed vegetable production systems at the area. The experiment was a randomized complete factorial design with two plastic mulch treatments (narrow vs. wide plastic mulch) and two rotation treatments (broccoli–zucchini–winter wheat vs. broccoli–zucchini–fallow). The narrow-plastic-mulch system has significantly (P < 0.05) increased runoff and soil loss than wide-plastic-mulch system. Results indicated that plastic mulch substantially accelerated runoff generation and soil erosion at vegetable seedling stages, whereas runoff and soil loss were apparently alleviated in furrow with residue mulch. The sediment transport played a predominant role in soil nitrogen (N) and phosphorus (P) movement by surface runoff. The annual losses of N and P via surface runoff in the vegetable field were ranged from 2.0 to 5.1 kg/ha and 0.3 to 1.1 kg/ha respectively in the three considerably drier rain season, but their losses never exceeded 1 % of the annual fertilizer application. Removal of crop residues was the major causes of N and P export from the soil in the vegetable fields, which exceeded 20 and 8 % of the annual nitrogen and phosphorus fertilizer application respectively. This implicated that inappropriately discarding of the residues would pose serious consequences for water contamination of Dianchi lake. As under appropriate discarding of residues, the wide-plastic-mulch system could improve NPS pollution control and crop production in vegetable field at Dianchi lake’s catchment.

The positive contribution of invertebrates to sustainable agriculture and food security.

Abstract This study focuses on three main groups of organisms: soil invertebrates, biological control agents (BCAs) and pollinators. These groups play key roles in agricultural systems, and have the potential to be used, moved or manipulated for the benefit of agriculture. Soil invertebrates are a key component of agricultural landscapes. They participate in essential soil processes that maintain healthy productive soils in the face of changing environmental conditions. Reducing the diversity of a community of soil invertebrates reduces its beneficial functions and services, with drastic ecological effects such as long-term deterioration of soil fertility and agricultural productive capacity. The introduction of a keystone species may have detrimental or beneficial effects depending on the context. The interaction between soil invertebrates and soil micro-organisms is critical: the activities of soil invertebrates regulate microbial activity in soils, and micro-organisms enter into intimate relationships with soil invertebrates to help them degrade highly complex compounds such as cellulose. Different groups of invertebrates provide biological control of crop pests. In many situations, they form the basis of, and tools for, the integrated pest management (IPM) approach. Given that the losses caused by pre- and post-harvest pests can be very substantial, the potential benefits of using invertebrates as BCAs are vast, but as yet only partially tapped. The potential for soil invertebrates to assist in this function is still largely unknown. Pollination services by animals, especially by insects, are among the most widespread and important processes that structure ecological communities in both natural and agricultural landscapes. An estimated 60-90% of the world's flowering plants - including a range of economically important species - depend on insects for pollination. Crop pollination used to be (and often still is) provided by wild pollinators spilling over from natural and semi-natural habitats close to crop fields. This service has generally been free and therefore has received little attention in agricultural management. If wild pollinators are lacking or additional pollination is required, as is the case in many intensive agricultural production systems, farmers in some developed countries can buy or rent managed honeybees or sometimes other species (e.g. bumblebees, alfalfa leafcutter bees and alkali bees). Both options - i.e. use of wild species and managed bees - have recently come under pressure, a development that is sometimes referred to as the 'pollination crisis'. Of the interactions and overlaps between these key groups, that between soil invertebrates and BCAs is the most important, and further research is needed to evaluate the scope and impact of manipulation of the soil ecosystem to conserve or encourage beneficial BCAs.

Nitrogen in global animal production and management options for improving nitrogen use efficiency

Animal production systems convert plant protein into animal protein. Depending on animal species, ration and management, between 5% and 45 % of the nitrogen (N) in plant protein is converted to and deposited in animal protein. The other 55%-95% is excreted via urine and feces, and can be used as nutrient source for plant (= often animal feed) production. The estimated global amount of N voided by animals ranges between 80 and 130 Tg N per year, and is as large as or larger than the global annual N fertilizer consumption. Cattle (60%), sheep (12%) and pigs (6%) have the largest share in animal manure N production. The conversion of plant N into animal N is on average more efficient in poultry and pork production than in dairy production, which is higher than in beef and sheep production. However, differences within a type of animal production system can be as large as differences between types of animal production systems, due to large effects of the genetic potential of animals, animal feed and management. The management of animals and animal feed, together with the genetic potential of the animals, are key factors to a high efficiency of conversion of plant protein into animal protein. The efficiency of the conversion of N from animal manure, following application to land, into plant protein ranges between 0 and 60%, while the estimated global mean is about 15%. The other 40%-100% is lost to the wider environment via NH(3) volatilization, denitrification, leaching and run-off in pastures or during storage and/or following application of the animal manure to land. On a global scale, only 40%-50% of the amount of N voided is collected in barns, stables and paddocks, and only half of this amount is recycled to crop land. The N losses from animal manure collected in barns, stables and paddocks depend on the animal manure management system. Relative large losses occur in confined animal feeding operations, as these often lack the land base to utilize the N from animal manure effectively. Losses will be relatively low when all manure are collected rapidly in water-tight and covered basins, and when they are subsequently applied to the land in proper amounts and at the proper time, and using the proper method (low-emission techniques). There is opportunity for improving the N conversion in animal production systems by improving the genetic production potential of the herd, the composition of the animal feed, and the management of the animal manure. Coupling of crop and animal production systems, at least at a regional scale, is one way to high N use efficiency in the whole system. Clustering of confined animal production systems with other intensive agricultural production systems on the basis of concepts from industrial ecology with manure processing is another possible way to improve N use efficiency.

Surface N balances and reactive N loss to the environment from global intensive agricultural production systems for the period 1970–2030

Data for the historical years 1970 and 1995 and the FAO-Agriculture Towards 2030 projection are used to calculate N inputs (N fertilizer, animal manure, biological N fixation and atmospheric deposition) and the N export from the field in harvested crops and grass and grass consumption by grazing animals. In most industrialized countries we see a gradual increase of the overall N recovery of the intensive agricultural production systems over the whole 1970-2030 period. In contrast, low N input systems in many developing countries sustained low crop yields for many years but at the cost of soil fertility by depleting soil nutrient pools. In most developing countries the N recovery will increase in the coming decades by increasing efficiencies of N use in both crop and livestock production systems. The surface balance surplus of N is lost from the agricultural system via different pathways, including NH3 volatilization, denitrification, N(2)O and NO emissions, and nitrate leaching from the root zone. Global NH(3)-N emissions from fertilizer and animal manure application and stored manure increased from 18 to 34 Tg x yr(-1) between 1970 and 1995, and will further increase to 44 Tg x yr(-1) in 2030. Similar developments are seen for N(2)O-N (2.0 Tg x yr(-1) in 1970, 2.7 Tg x yr(-1) in 1995 and 3.5 Tg x yr(-1) in 2030) and NO-N emissions (1.1 Tg x yr(-1) in 1970,1.5 Tg x yr(-1) in 1995 and 2.0 Tg x yr(-1) in 2030).

DENSITY AND DIVERSITY OF OVERWINTERING BIRDS IN MANAGED FIELD BORDERS IN MISSISSIPPI

Grassland bird populations are sharply declining in North America. Changes in agricultural practices during the past 50 years have been suggested as one of the major causes of this decline. Field-border conservation practices encouraged by the U.S. Department of Agriculture's National Conservation Buffer Initia- tive meet many of the needs of sustainable agriculture and offer excellent opportunities to enhance local grassland bird populations within intensive agricultural production systems. Despite the abundant information on avian use of, and reproductive success in, strip habitats during the breeding season, few studies have examined the potential value of field borders for wintering birds. We planted 89.0 km of field borders (6.1 m wide) along agricultural field edges on one-half of each of three row crop and forage production farms in northeastern Mississippi. We sampled bird communities along these field edges during February-March 2002 and 2003 using line-transect distance sampling and strip transects to estimate density and community structure, respectively. We used Program DISTANCE to estimate densities of Song (Melospiza melodia), Savannah (Passerculus sand- wichensis), and other sparrows along bordered and non-bordered transects while controlling for adjacent plant community. Greater densities of several sparrow species were observed along most bordered transects. However, effects of field borders differed by species and adjacent plant community types. Diversity, species richness, and relative conservation value (a weighted index derived by multiplying species-specific abundances by their re- spective Partners in Flight conservation priority scores) were similar between bordered and non-bordered edges. Field borders are practical conservation tools that can be used to accrue multiple environmental benefits and

Nitrate leaching and pasture production from different nitrogen sources on a shallow stoney soil under flood-irrigated dairy pasture

The leaching of nitrate (NO3–) in intensive agricultural production systems, e.g. dairy pastures, is a major environmental concern in many countries. In this lysimeter study we determined the amount of NO3– leached following the application of urea, dairy effluent, urine returns, and pasture renovation to a freedraining Lismore stony silt loam (Udic Haplustept loamy skeletal) growing a mixture of perennial ryegrass (Lolium perenne) and white clover (Trifolium repens) pasture. The study showed that NO3–-N leaching losses ranged from 112 to 162 kg N&amp;sol;ha per year, depending on the amount and forms of N applied and pasture conditions. Nitrate leaching under the urine patches was the main contributor to the N leaching loss in a grazed paddock. Nitrate leaching losses were lower for urine applied in the spring (29&amp;percnt; of N applied) than for urine applied in the autumn (38–58&amp;percnt;). The application of urea or dairy effluent only contributed a small proportion to the total NO3– leaching loss in a grazed paddock. Pasture renovation by direct-drilling may also have caused an increase in NO3– leaching (c. 31 kg N&amp;sol;ha) in the first year. Modelled annual average NO3–-N concentrations in the mixed recharge water in the acquifer were significantly lower than those measured under the rooting zone due to dilution effects by recharge water from other sources (3.9 v. 13–27 mg N&amp;sol;L). Herbage nitrogen offtake and dry matter yield were higher in the urine treatments than in the non-urine treatments. groundwater, denitrification, mineralisation, grazing, forage.