Impact Of Agricultural Practices Research Articles

QUALITY IN CHAINS: CONSUMERS AND RISK

QUALITY IN CHAINS: CONSUMERS AND RISK

IONIC CONCENTRATIONS IN SURFACE WATERS OF AN AGRICULTURAL CATCHMENT DURING STORM EVENTS

Agricultural pollutants are generally carried to water courses by storm flows and infiltration waters. Because of this, their higher impact on water quality usually takes place after big rain events. This behavior emphasizes the importance of water quality studies carried out in agricultural catchments involving storm events. The results shown in this report were obtained from analyses of electric conductivity and concentrations of Ca++, Na+, K+, Cl−, NH4 +, and NO3 − in samples collected during four storm events in a small agricultural catchment receiving frequent cattle and pig slurry applications. All the analysis were carried out with a multiparametric probe equipped with ion-selective electrodes. In general, higher ion concentrations were observed in the first stages of storm events and were followed, in most cases, by concentration decreases, sometimes registered before the stream reached its maximum flow rate. The most probable explanation for this behavior is related to the arrival of runoff water carrying materials proceeding from slurry applications to the stream. Dragging of these materials is promoted by the formation of a surface crust on the top soil of the fallow land that represents approximately half of the area being studied. Later on, continuous flow increase promotes a dilution effect that leads to a fall in the ion concentrations. The low base-flow index of the catchment (0.47) have an influence too on this behavior by making most of ions are transported by runoff. The only ion that showed strong differences when compared with the general behavior is Na+, whose concentrations seem to be mostly governed by dilution effects. In this case, measurements taken during high flows showed concentrations similar to, or even lower than those obtained from base flows. N− NO3 − y N− NH4 + discharges were calculated for each event and stated as percentages of total annual discharge. These results were compared with percentages of water discharge to asses the quantitative importance of N losses in storm events related to total losses. N− NO3 − losses were higher in 3 of the 4 selected events, reaching in one of them 11.3% of total N− NO3 − losses. N− NH4 + losses showed the opposite behavior. The aim of this work is getting progress in the knowledge of agricultural pollutants transport dynamics. Advances in this knowledge are of capital importance to minimize the impact of agricultural practices in water bodies.

Linking agricultural practice to insect and bird populations: a historical study over three decades

Summary There is continuing debate about the impact of agricultural practices on farmland wildlife. In particular, it has been postulated that a general decline in insect abundance linked with intensification of agriculture may have contributed to farmland bird decline. While some autecological studies have supported this hypothesis, larger‐scale and long‐term studies are needed. Suction traps mounted on 12·2‐m towers (Rothamsted‐type) have been sampling aerial insects for nearly 40 years throughout the UK. Their catches are correlated over large spatial scales. We analysed insect catch data from a single suction trap run for 27 years in a rural location in Scotland, and showed that insect numbers have changed significantly over time, although non‐linearly. The multivariate data set (numbers from the 12 common arthropod groups) was summarized using principal components analysis (PCA) to extract three components explaining 62% of the variation. We also used PCA to describe agricultural change, using published agricultural data for eight measures of farming in Scotland. Arthropod abundance and principal component (PC) scores were significantly related to the agricultural PC scores as well to summary climatic measures. Using Scottish data from the British Trust for Ornithology Common Birds Census, we extracted three PC to describe the time‐dependent average densities of 15 common farmland birds in Scotland. Measures of bird density were significantly related to insect abundance and PC scores and, independently, to measures of agriculture and climate. These data from a broad suite of species provide support for linked temporal change between farmland birds, invertebrate numbers and agricultural practice in Scotland. Although entirely correlative, the results are consistent with the view that agricultural change has influenced birds through changes in food quality or quantity. The work also shows how large‐scale invertebrate sampling, in this case using suction traps, is useful for monitoring farmland biodiversity.

Implementation of best management practices in agriculture: modelling and monitoring of impacts on nitrogen leaching

In Kattegat and the coastal water of the Baltic Sea, high nitrogen input from agricultural land is considered to be the main reason for eutrophication. International agreements and governmental programs have set a target to reduce the anthropogenic nitrogen load by 50 percent. Improved nitrogen removal in treatment plants and efforts in agriculture have so far not decreased nitrogen transport to a sufficient extent. In this project the impact of agricultural practices on nitrogen leaching was investigated in two small agricultural catchments in Southwest Sweden. The root-zone leaching was estimated by an indexing technique. Simultaneously the transports in the stream outlets were monitored. During 1995 and 1999 the agricultural practices in the catchments were surveyed. Field data from the first survey indicated that fertilisation did not always match crop requirements, the area of undersown catch crop can be increased and autumn cultivation can be reduced. The second survey was preceded by an advisory campaign where each farmer was visited and presented with an environmental plan including fertilisation, cultivation, and crop rotation for the farm. The plan summarised the best management practices that could be realised under actual conditions. Results from the second survey showed that some changes in the agricultural practices were carried out after the advisory campaign. The nitrogen leaching from the root-zone was then estimated by the indexing technique, both for the time before and after the advisory program. The results showed that the estimated nitrogen leaching, as a mean value for 330 fields, decreased from 53 to 50 kgN ha(-1), due to adjustments of the agricultural practices. Monitoring of stream transports showed values of the same magnitude after correction for retention and other sources. In this short time perspective, decreases in transport due to changes in agricultural practices could not be separated from influence of weather conditions. In comparison to results from the Swedish monitoring programme for agriculture, the measured transports were normal for the region, where annual variation in precipitation and runoff is large. Theoretically, nitrogen leaching could be reduced by one third without any major economic constraints for the farmers. In general, the farmers were positive to advice and willing to try new farming techniques even if some measurements were not fully implemented during the investigation period.

Effect of agro-activities on drinking-water quality in Bangladesh

Fifty-nine samples of drinking water were collected from various locations in Bangladesh to assess the impact of agricultural practices on groundwater quality. The basic groundwater quality parameters, such as pH, total dissolved solids, iron, sodium, chloride, sulfate, fluoride and arsenic were analysed. In addition, the presence of excess fertilizers was monitored by measuring levels of ammonium, nitrate, phosphate and potassium, and the presence of excess pesticides by measuring levels of endrin, heptachlor and DDT. The results were evaluated on the basis of drinking-water quality standards for Bangladesh as well as WHO and EC standards. Water samples were found to contain relatively high concentrations of ammonium, nitrate and iron. The ranges of the organochlorine pesticides heptachlor and DDT were 0.025-0.789 mg/l and 0.010-1.527 mg/l, respectively. Two samples violated the allowable limits for heptachlor, seven for DDT. The presence of low levels of persistent pesticides at certain locations, along with higher than normal levels of ammonium and nitrate clearly demonstrates that agro-chemicals have influenced the water quality of groundwater sources in Bangladesh.

Consequences of less intensive farming on the landscape: an example of vegetation dominance by Chaerophyllum aureum in the meadows of a Pyrenean valley in France

The impact of agricultural practices on the dynamics of weed invasion in a rural landscape was studied by describing the spatial distribution of Chaerophyllum aureum populations colonising less intensive managed hay meadows. Polyphenol compounds were used as individual markers to identify the structure of C. aureum diversity, in terms of its scale and patterns, within and between fields along the bottom of a Pyrenean valley. The results revealed, firstly, the existence of a dominant `genotype' successfully colonising the entire area, and secondly, the maintenance of high levels of polyphenol diversity within five different populations. This spatial arrangement of `genetic' population diversity was obviously not related to the natural reproduction and dispersal patterns of this species, but to human practices of hay production, the principal effect of which is to mix seeds of different genetic origin and thus accelerate and amplify the colonisation process of adapted `genotypes'.

Phosphorus Status of Intensively Cropped Soils of the St. Lawrence Lowlands

The P saturation degree of agricultural, neutral to slightly alkaline soils in areas where P fertilization is mainly inorganic is relatively unknown. The objective of this study was to determine the P status of the whole profile of 27 intensively cropped soils from an area receiving mainly inorganic fertilizers, the St. Lawrence lowlands in the province of Quebec, Canada, and to compare their P status to soils from a very different agrosystem with high animal density in the Appalachians. The A, B, and C horizons of nine soil series (three sites per soil series) showing a gradient in clay content were collected and analyzed for their Mehlich‐III extractable P (M3P), water‐soluble P (Pw), organic P (Po) and total P (Pt) contents. The P sorption index (Psi) and the P saturation degree (Pox/(Alox+Feox)) were also determined. Nine of the 27 studied fields exceeded 112 mg M3P kg−1, the level considered as excessive for corn (Zea mays L.) and soybean [Glycine max (L.) Merrill]. The results suggest that the impact of agricultural practices on the soil P status in the lowlands was mainly limited to the A horizon as few sites had elevated labile P contents or saturation degree in their subsoils. Compared to long‐term manured, acidic soils from a high animal density watershed, neutral to slightly alkaline soils from the lowlands had much lower Pt contents and the proportion of Pt as Po was also two to three times lower. However, given their low to medium P sorption capacity, P saturation degree of the A horizons was comparable to soils from the high animal density watershed.

Impact of agricultural practices on a small headwater stream: terrestrial and aquatic characteristics and self-purifying processes.

The objective of this work was to study the drainage basin of a small crater lake whose short tributary runs through pastureland and ponds. The catchment was separated into four morphological units and core sampling was carried out to analyze pedological horizons. Five stations were surveyed along the stream. The water quality was investigated seasonally through both physical and chemical variables (oxygen, pH, temperature, phosphorus, nitrate) and with the French normalised biological index. The analysis of macroinvertebrates was made with regard to the spatial heterogeneity of the streambed and the community structure, then categorized by habitat preferences and functional feeding groups. The land at the top of the catchment area, consisting of hydromorphic soils, was used for cattle breeding. This generated the increase in suspended sediment and nutrients concentration in the water. However, the decrease in nutrients from up to downstream, and the evolution of the benthic communities, indicated an improvement in water quality. The high degree of self-purification in the catchment area may result from the combined action of ungrazed hydromorphic soils, ponds and natural purification of the stream. Moreover, the geomorphological characteristics of the catchment influence physical and chemical variables, as well as the biological traits of the macroinvertebrates. As a consequence, the indices of taxa diversity, weighted according to substrates types, seemed to be the most accurate descriptors of the environmental changes. Thus, the resilience of the aquatic ecosystem may be influenced by the degree of complexity of the watershed geomorphology.

Overview of the biogenic sources of atmospheric trace compounds due to agricultural activities

All human activities profoundly affect the chemical composition and properties of the atmosphere. The present overview highlights the impact of agricultural practices, including livestock raising, on the biogeochemical cycles of carbon and nitrogen and discusses the relevant environmental issues. Emissions from agriculture significantly contribute to the atmospheric budget of methane and nitrous oxide, which in turn contribute to the greenhouse effect. Agricultural activities are also the predominant source of ammonia to the atmosphere, so affecting the acidity of atmospheric depositions. A minor role is expected from agriculture in the production of tropospheric ozone through nitrogen oxides and volatile organic compound emissions.

Burlington Bay, Lake Ontario: Its Paleolimnology Based on Fossil Ostracodes

Abstract The history of Burlington Bay for the last 8,400 years has recorded two significant changes in its environment. The first occurred about 2,540 years ago, resulting from a change in mean annual temperature. This, in turn, changed the chemistry of the bay water. The second change occurred about 125 years ago (ca. 1865 A.D.). This time, it was the impact of agricultural practices and industrialization. Agricultural practices caused the lake to become eutrophic. This rapidly (within 40 years) changed the bottom water oxygen conditions to anaerobic. Industrialization had an impact on the fauna and the flora. Some fauna became locally extinct while some phytoplankton became deformed.

The impact of agricultural practices on biodiversity

Agricultural activities such as tillage, drainage, intercropping, rotation, grazing and extensive usage of pesticides and fertilizers have significant implications for wild species of flora and fauna. Species capable of adapting to the agricultural landscape may be limited directly by the disturbance regimes of grazing, planting and harvesting, and indirectly by the abundance of plant and insect foods available. Some management techniques, such as drainage, create such fundamental habitat changes that there are significant shifts in species composition. This paper considers the relative merits of conventional tillage versus reduced, or no-till farming, and reviews the benefits of rest-rotation grazing, crop rotation and intercropping in terms of maintaining wild species populations. There are a number of undesirable environmental impacts associated with fertilizer and pesticide usage, and in this paper we attempt to provide an account of the ways in which these inputs impact on biodiversity at various levels including plant, invertebrate, and vertebrate groups. Factors which are considered include the mobility, trophic interactions, persistence, and spectrum of toxicity for various pesticides. The ecological virtues of organic and inorganic fertilizers are compared, and the problems arising from excessive use of fertilizer are discussed. The findings in this review indicate that chemical fertilizer loadings must be better budgeted to not exceed local needs, and that pesticide inputs should be reduced to a minimum. The types and regimes of disturbance due to mechanical operations associated with agricultural activity may also be modified to help reduce negative impacts on particular groups of species, such as birds. For those plant and insect species which need to be controlled for agronomic reasons, the population decreases brought about by disturbance regimes may be desirable as a form of pest management. The prevalence of agriculture over such a large portion of the Canadian landscape means that it is important that we find solutions to conflicts that arise between agriculture and wild species. It is important to realize that the impact of agricultural inputs varies greatly among regions and species, and actual effects have generally not been investigated for many species in any one locality; while the focus of this review is on Canada, much Canadian-specific research is lacking, thus, this review also draws from relevant research done elsewhere.

Impact of agricultural practices on the size and activity of the microbial biomass in a long-term field experiment

The Deherain long-term field experiment was initiated in 1875 to study the impact of fertilization on a wheat-sugarbeet rotation. In 1987, the rotation was stopped to be replaced by continuous maize. Crop residues were soil-incorporated and the mineral fertilization was doubled in some plots. The impact of those changes on the microbial biomass and activity are presented. In spring 1987, the soil was still in a steady-state condition corresponding to the rotation. The microbial biomass was correlated with total organic C and decreased in the order farmyard manure>mineral NPK>unfertilized control. Microbial specific respiratory activity was higher in the unfertilized treatments. The soil biomass was closely related to soil N plant uptake. In 1989, after 2 years of maize and crop residue incorporation, the steady-state condition corresponding to the previous agricultural practices disappeared. So did the relationship between the biomass and total organic C, and the soil N plant uptake. Biomass specific respiratory activity increased because of low efficiency in the use of maize residues by microbes under N stress.

Impact of agricultural practices on soil food web structure: Theory and application

Studies on the effects of agricultural practices have increasingly taken a a systems perspective. A comparison of five long-term (5–10 year) systems level studies on native and agricultural soils ranging from the North American Shortgrass Steppe to recent Polder soils in the Netherlands demonstrates that systems exhibit common responses to agricultural disturbances. For example, management practices that incorporate organic material (stubble-mulching and conventional practices) disrupt the temporal and spatial compartmentalization of the bacterial and fungal energy channels of soil food web. Under these practices, the bacterial energy channel tends to be more active than the fungal energy channel. However, management practices that minimize the disruption of top-soil (notillage and integrated farming) tend to maintain temporal and spatial compartmentalization of the bacterial and fungal energy. In these practices, the fungal energy channel is either dominant or is more active than in more disturbed sites in the same soils. Coincident with the change in structure are changes in nutrient dynamics. Having established patterns in the ways in which agricultural practices alter food web structure and function, the challenge will be to utilize this knowledge in the development of sustainable low-input agricultural systems.

Impacts of agricultural practices on aquatic oligochaete populations in ricefields

The impacts of N fertilizer, pesticides and green manure on aquatic oligochaetes in irrigated ricefields were investigated in experimental plots. Populations, determined by the wet sieving of soil cores, were dominated by the Tubificidae Limnodrilus hoffmeisteri. Total densities ranged from 0 to 40 000 m-2. Oligochaete numbers increased in response to additions of urea N. An inhibitory effect of carbofuran on oligochaete populations was observed during the first season of experimental pesticide treatments, but not during the following year. The green manure Sesbania rostrata stimulated population development more than Azolla microphylla. Populations in plots maintained as wet fallow remained low throughout the crop cycle. Population dynamics were associated with the crop cycle. Peak densities were achieved 30–50 days after transplanting.

A comparison of sampling techniques and summary indices for assessment of water quality in the Yamaska River, Qu�bec, based on benthic macroinvertebrates

The Yamaska River drainage basin in Quebec, Canada, is intensively farmed and heavily polluted with poorly treated domestic and industrial wastes. We investigated the responses of the resident and colonizing components of the benthic macroinvertebrate community to municipal/industrial versus agricultural pollution in the basin, and evaluated the performances of seven diversity and biotic indices for assessing water quality. Samples of riffle-dwelling, infaunal and colonizing invertebrates were collected from 13 stations representing a wide range of types and degrees of pollution using Surber, scoop and artificial substrate samplers. The data were summarized using the indices S (number of taxa), N (number of individuals), H' (Shannon-Wiener's diversity index), D (Simpson's diversity index), BBI (Belgian Biotic Index), TBI (a modification of Hilsenhoff's Biotic Index), % CHIR (percentage of arthropods consisting of Chironomidae) and %OLIGO (percentage of total organisms consisting of Oligochaeta). Different components of the community generated somewhat different assessments and were, therefore, complementary. Community composition, expressed as the percentage of individuals contributed by major taxonomic groups, reflected the kinds of stresses at a station more consistently than did any of the indices. S and TBI came closest to ranking control, agricultural and municipal/industrial sites in accordance with our a priori classification, both between months and among sampling methods. %OLIGO usually separated municipal/industrial sites from control sites. Other indices were found to be less sensitive, accurate or temporally stable, or were otherwise inappropriate for use with certain sampling methods or for certain types of pollution. With most of our samples, all of the summary indices suggested that the impact of agricultural practices on stream ecosystems may be as severe as the impacts of municipal and industrial wastes.

Impact of Agricultural Practices on Soil Pollution

Soils are the base resource for food production yet agricultural activities can result in long-term damage. This paper focuses on the problems that result from high inputs of plant nutrients, from fertilizers or animal excreta, and from the pesticides that are associated with intensive production. Concern is not only about the direct effects on soils but also on leakages to both water and the atmosphere. Fortunately, the problems are becoming increasingly well recognized—but is it too late to prevent irreversible damage?

Impact of agricultural practices on groundwater salinity

The impact of agricultural practices on water quality has been examined predominantly with an emphasis on surface water. Impacts on groundwater, as compared with surface waters, are much more difficult to quantify. This is due to larger travel times to and in groundwaters as compared with surface waters and difficulty in sampling groundwaters properly. Despite these difficulties in quantification, the impacts on ground- and surface waters are equally important. In non-irrigated areas agriculture often leads to increased recharge, sometimes resulting in the leaching of salts from the unsaturated zone into groundwater. In irrigated areas groundwater salinization can result from irrigation with saline water, salt water intrusion owing to pumping of groundwater, downward movement of salts in the unsaturated zone or dissolution of saline minerals, and from the unavoidable concentration of salts owing to plant water uptake. The interrelationship of surface and groundwaters must involve water quality as well as quantity. Optimization of water resources entails consideration of conjunctive use, which in turn requires consideration of water quality in all parts of the system. In this paper examples are given showing how improvements made to reduce river salinity can cause groundwater salinization, which may not represent the optimum management strategy.

Succession of Mammals in a Disturbed Area of the Great Plains

Effects of historic and continuing disturbance on the flora and mammalian fauna at Barr Lake State Park, Adams County, Colorado, were assessed. Construction of an impoundment and irrigation canal enabled development of a riparian zone that initially increased the richness of the mammalian fauna by nine species. Subsequent conversion of nearby rangeland to cropland decreased the richness of the fauna by as many as 12 species. Mid-summer drawdown of the lake for irrigation possibly promotes disturbance vegetation and disrupts populations of small mammals. Agricultural practices on the Great Plains have had both pronounced and subtle effects on native prairie. Some of these effects are intensified by sparse precipitation or by agricultural activities intended to circumvent sparse precipitation. Although agricultural activity has increased in recent years, the effects of these practices on the native flora and fauna of the Great Plains have received little attention. Grant et al. (1982) investigated the impacts of grazing on structure of vegetation and composition of small mammals, whereas Moulton et al. (1981) hypothesized that native species of mammals eventually recolonize areas subjected to disturbance if adequate avenues of dispersal exist and if the structure of the vegetation remains similar. Most studies of the impact of agricultural practices on the plains (e.g., Judd and Jackson, 1939; Costello, 1944; Judd, 1974) focused on secondary succession of plants leading toward reestablishment of natural plant communities on abandoned cropland after termination of alternative practices. The objectives of this investigation were to compare the historic flora and mammalian fauna with those currently found at Barr Lake State Park, Adams County, Colorado, and thereby to characterize succession of mammals in an area of the Great Plains subjected to continuing disturbance.

Agricultural Scientists as Reluctant Revolutionaries

AbstractThe productivity of modern agriculture is a result of a remarkable fusion of technology and science. The emerging skepticism about the role of science in society has led to a questioning of the benefits from technical change in agriculture and there is a rising demand for more effective social control over the development and use of agricultural technology. Agricultural science cannot evade responsibility for the costs as well as the benefits of technical change. But it is in society's interest to let the burden of responsibility rest lightly and to insist that agricultural science maintain its commitment to expanding the productive capacity of the resources used in agricultural production. But society should also insist that agricultural science embrace an agenda that includes a concern for the effects of agricultural technology on the health and safety of agricultural producers; a concern for the nutrition and health of consumers; a concern for the impact of agricultural practices on the aesthet...

The Impact of Agricultural Practices on Water Resources

The approach to water resources planning which is being used by Thames Water Authority is discussed. This involves consideration of uncertainty in future climate, demand and water quality. The reliability of supply is expressed in terms of the effects felt by the consumer. The recent increases in river nitrate concentrations are related to agricultural practices and predictions are made of possible future concentrations. The effect that these would have on the reliability of water resources is discussed.