High Chemical Input Research Articles

Sediment quality of the Neuse River estuary, North Carolina: an integrated assessment of sediment contamination, toxicity, and condition of benthic fauna

A study of ecological conditions associatedwith bottom sediments in the Neuse Riverestuary, U.S.A. was undertaken during summer1998. Sampling of macroinfauna, sedimentsfor toxicity and chemical contaminant analyses,and physical properties of water was carriedout synoptically over a four-day period at 20stations from the mouth of the Neuse River atPamlico Sound to approximately 90 km upstream. The distribution and condition of benthicinfauna were found to vary in response tonatural and anthropogenic factors, and apparentassociations between degraded infaunalcondition and sediment contamination and/ortoxicity were observed over roughly half of thesampled area (7 stations, 47% area). With fewexceptions, degraded benthic conditions wereassociated with significant sedimentcontamination or toxicity. High sedimentcontaminant levels were found to occur almostexclusively in fine-grained, organic-rich muds. These results suggest that high organic loadingand chemical contaminant inputs to the NeuseRiver, coupled with low freshwater dischargerates and high residence times in the lowerestuary, have contributed to degraded benthicconditions at these sites.

WEED ABOVEGROUND AND SEEDBANK COMMUNITY RESPONSES TO AGRICULTURAL MANAGEMENT SYSTEMS

The development of integrated weed management programs requires a clear understanding of the factors and mechanisms conditioning weed community dynamics in agroecosystems. This study evaluated the effect of different agricultural management systems on the aboveground and seedbank weed communities in annual row crops at the Long Term Ecological Research project in agricultural ecology at the W. K. Kellogg Biological Station, Michigan, USA. Weed biomass and species composition were sampled for six years over two corn–soybean–wheat sequence cycles in four agricultural management systems: (1) conventional (high external chemical input, moldboard plowed); (2) no-till (high external chemical input, no tillage); (3) low-input (low external chemical input, moldboard plowed); and (4) organic (no external chemical input, moldboard plowed). A greenhouse germination study assessed variation in the abundance and composition of the weed seedbank across the studied systems in the first and sixth year of this study. Abov...

Sex ratio alterations in terrestrial woodlice populations (Isopoda: Oniscidea) from agroecosystems subjected to different agricultural practices in Italy

The influence of different agricultural practices on the sex ratio shown by Trachelipus rathkei (Isopoda: Oniscidea) populations was investigated by pitfall trapping in three nearby sites from an agricultural landscape in northern Italy, a conventional, high chemical input apple orchard, a biological, no chemical input apple orchard, and an uncultivated deciduous forest. In the forest site, the sex ratio changed from a significant male-bias during the first part of the annual activity period to a female-bias during the last part of the activity season. In the conventional orchard, however, the sex ratios showed a female-bias during the whole activity period. The biological orchard population showed a temporal pattern rather similar to that found in the forest population. These results are congruent with the hypothesis that distorted sex ratios, and especially female-biased ones, are likely to arise within populations subjected to one higher environmental disturbance. Accordingly, biological agriculture, at least in this case, could be considered as a gentler, less disturbing anthropogenic disturbance for isopod populations, so allowing the maintenance of more natural ecological features relatively to modern conventional, high chemical input agriculture. The adaptive, environmental and bioindicative significance of these results are discussed.

Productivity and profitability of multistrata organic versus conventional coffee farms in Costa Rica

In areas where traditional multistrata coffee systems have been transformed to systems with patchy or no shade at all, often dependent on high chemical inputs, ecological and socioeconomic degradation has become an increasing issue. During the 1990s, rising environmental and health concerns have promoted the interest in organic production systems and their environmental services for natural resource conservation. This study compared productivity, profitability, producer-defined constraints, and goals and research priorities between ten individually paired organic and conventional coffee farms in Costa Rica. Although five of the organic farms matched or exceeded the production of their conventional counterparts, the three-year mean yield of the organic farms as a group was 22% lower than that of the conventional farms. However, excluding organic certification costs, mean variable costs and net income (NI) were similar for both groups, mainly because organic price premiums received by the farmers compensated for lower yields. If current organic certification costs are included, the price premiums paid to organic producers would have to increase to 38% in order to equal the NI from conventional coffee. Conventional farmers indentified low and unstable prices as the main constraints to sustained production and stated further intensification of production as their main goal. In contrast, the key issues for future development of the organic group centered on farm diversification, agroecological self-sufficiency, and agronomic practices that permit organic farm management.

Environmental and human costs of commercial agricultural production in South Asia

In writing a paper to honour Professor Clem Tisdell, it is apt to focus attention on the environmental and human costs of commercial agricultural production, especially the Green Revolution technology in South Asia during the last few decades. This is an area where Professor Tisdell has done much research, amongst the multitude of other research interests he has pursued in his very illustrious career. Modern commercial agricultural practices involving chemical inputs such as fertilizers and pesticides have been associated with huge increases in food production never witnessed before and, in the case of cereal production (especially wheat) under Green Revolution technology, recorded spectacular growth. As statistics show, production and productivity have increased. However, the high chemical usage of fertilizers and pesticides to bring about these spectacular increases in food production is not without its problems. A visible parallel correlation between higher productivity, high chemical input use and environmental degradation and human health effects is evident in many countries where commercial agriculture is widespread. This paper discusses the environmental and health effects/costs arising from the high use of chemical inputs to increase production and productivity in South Asia, with a field study carried out in Sri Lanka to show the health costs arising from direct exposure to pesticides during pesticide handling and spraying on farms by small‐scale farmers.

Tillage × Rotation × Management Interactions in Corn

Although corn (Zea mays L.) yields following soybean [Glycine max (L.) Merr.] or wheat (Triticum aestivum L.) exceed yields of continuous corn, continuous corn is common in the northeastern USA because of demand for corn by the dairy industry. We evaluated corn under different tillage (moldboard plow, chisel, and ridge), rotation (continuous corn, soybean–corn, soybean–corn–corn, and soybean–wheat/red clover (Trifolium pratense L.)–corn), and management systems (high and low chemical input) for 6 yr to determine optimum cropping systems for corn. In moldboard plow, corn in soybean–wheat/red clover–corn (9.2 Mg ha−1) and soybean–corn (8.5 Mg ha−1) rotations under low chemical yielded greater than continuous corn under high chemical management (7.9 Mg ha−1). In chisel tillage, corn in the soybean–corn rotation yielded greater under high chemical (8.9 Mg ha−1) and similarly under low chemical (7.9 Mg ha−1) compared with continuous corn under high chemical management (7.6 Mg ha−1). In ridge tillage, corn in soybean–corn or first‐year corn in soybean–corn–corn rotations yielded greater under high chemical (8.1 Mg ha−1) but less under low chemical (6.3 and 6.8 Mg ha−1, respectively) compared with continuous corn under high chemical management (7.5 Mg ha−1). Growers under similar environmental conditions to this study can increase corn yields while reducing inputs by adopting soybean–wheat/red clover–corn and soybean–corn rotations in moldboard plow or a soybean–corn rotation in chisel tillage. In ridge tillage, growers could adopt soybean–corn or soybean–corn–corn rotations, which would increase corn yields but not reduce inputs when compared with continuous corn.

Earthworm and enchytraeid activity under different arable farming systems, as exemplified by biogenic structures

A study was conducted in order to compare soil faunal activity in four experimental farming systems using different tillage, chemical input and crop rotation practices: A conventional system with deep-ploughing (CT), an integrated system with reduced tillage and minimum chemical input (IN), a system with reduced tillage and high chemical input (RT) and a system with minimum tillage and high chemical input (MT). In nine experimental fields with two sampling points each, earthworms were sampled and biogenic structures were identified and counted in topsoil profiles (0–14 cm depth). Components of these profiles were identified by morphological features. Quantitative analyses of these morphological features provided information about soil compaction, earthworm and enchytraeid activity and distribution of roots and crop residues in the soil matrix. The dominant species in the earthworm community was the endogeic Aporrectodea rosea. Earthworm densities were unexpectedly lowest under reduced tillage (6 specimens per m2), and highest under deep-ploughing (67 specimen per m2), the reverse effect being observed with enchytraeid worms, as ascertained by deposition of their faecal pellets in topsoil profiles. Strong very fine granular structure (STVFGR) was most frequent in the integrated farming system (IN). We concluded that in the studied site embracing four farming systems, enchytraeids play an important role in creating a stable soil structure and porosity at the low level of earthworm densities found in the integrated system (IN).

Agrichemical movement in the root-zone of claypan soils: ridge- and mulch-tillage systems compared

Climate, poor internal drainage in claypan soils, and cultural factors make it difficult to control agrichemical movement in the southern fringe of the Corn Belt, USA. Ridge- and mulch-tillage systems were evaluated for root-zone water quality and grain production on a claypan soil. In northcentral Missouri the Mexico silt lam (fine, montmorillonitic, mesic Udollic Ochraqualfs; FAO-Mollic Planosols) has a pronounced B t horizon. Zero-tension pan lysimeters at 91 cm were used to monitor nitrate–nitrogen (NO 3–N) and herbicide concentrations in three farming systems: (1) a high chemical input mulch-tillage in a corn ( Zea mays L.)–soybean [ Glycine max (L.) Merr.] rotation (MTH); (2) a reduced chemical input with mulch-tillage in a corn–soybean–wheat ( Triticum aestivum L.) rotation (MTR); (3) a reduced chemical input with ridge-tillage in a corn–soybean rotation (RTR). Farming system treatments were replicated three times with lysimeters placed in two replications. By band-applying herbicide over rows, herbicide mass applied to the MTR and RTR system was 50% less than applied to MTH, where herbicides were broadcast. Only marginal benefits to root-zone water quality could be attributed to this reduced herbicide input. Leachate water flow volume and chemical concentration intercepted by the pans were influenced more by intrinsic, site-specific soil hydrology and year-to-year variation of rainfall intensity and timing than by the management. Root-zone leachate in both MTH and RTR farming systems in 1992 were below USEPA maximum contaminant levels (MCL) of 10 mg l −1 for NO 3–N and 3 μg l −1 for atrazine used for drinking water. Rainfall after herbicide application was more frequent and intense in 1993, but the extent of leaching was site-specific with significant variation among plots within all treatments. For example, maximum NO 3-N and atrazine concentrations in leachate were 42 mg l −1 and 100 μg l −1, respectively, in one MTH plot, and in second plot they were below 7 mg l −1 and 2 μg l −1, respectively. High concentration variability also occurred between RTR plots. Nitrate–N and atrazine were consistently below their MCL on MTR plots. While herbicide movement and loss may be slightly reduced with banding, this management will have low adoption on claypan soils because of the yield-loss risks associated with the small time window allowed for field operations. The same risk is associated with split N applications.

Assessing nematode communities in agroecosystems of varying human intervention

The effect of disturbance on soil nematode communities was studied in eight treatments varying in intensity of human intervention at the Kellogg Biological Station Long Term Ecological Research site, Hickory Corners, MI. The agricultural treatments ranged from those manipulated with high chemical inputs and heavily impacted by human management to successional treatments that had no chemicals and little human impact. A canonical discriminant analysis of the nematode data separated the treatments into four systems: high chemical input (the conventional tillage and no tillage treatments, both corn/soybean rotations); organic (the low input and zero input treatments, both wheat/corn/soybean rotations); perennial (poplar and alfalfa treatments); successional (abandoned after tillage and never tilled treatments). Nematode abundance was highest in the high input and organic systems and lowest in the poplar treatment. Overall, bacterial feeding, plant parasitic and fungal feeding nematodes dominated the treatments. Species diversity was greatest in the successional treatments. The bacterial feeding trophic group and the modified Shannon index described differences at both the treatment and system levels, while the Shannon index demonstrated diversity at the system and annual and perennial crop level of analysis. Measures that detected differences ( P < 0.05) consistently across all treatments, systems, and annual vs. perennial crops were total abundance, the predator trophic group, the maturity index (MI) and the plant parasite index. The minimum analyses needed to detect disturbance reliably were a multivariate analysis and the MI. However, understanding and predicting the impact of the disturbance on the food web and ecosystem functioning would be increased with results from diversity indices and nematode functional groups.

A Model of Indigenous Revival for U.S. Agriculture

The agricultural industry is at an important crossroads in its history. Many believe that further shakeout and consolidation within U.S. agriculture is necessary, and few hold a great deal of hope for the survival of the small family farm. This paper presents a model of revitalization for the agricultural industry which focuses on the small farm and rural community rather than on further consolidation of the industry into the hands of large agribusinesses. The agricultural industry is criticized for attempting to respond to growth and consolidation of its input and output environments by consolidating its own activities, hence moving from diverse crop and stock, high labor intensity, family farming to low diversity row crop, high chemical input, agribusiness. In so doing, the agricultural industry and the rural community have reduced the economic diversity and self-sustaining capacity which were their true source of economic leverage. As a result, the agricultural community has lost economic influence. Th...

THREE ALTERNATIVE TOMATO PRODUCTION SYSTEMS

Tomatoes, cultivar `Mountain Pride', were evaluated for productivity, post-harvest qualities, and pest populations in three different production systems. These included a conventional, high chemical input system with prophylactic applications of pesticides and fertilizers; a reduced chemical input system that used pesticides only as needed; and a transitional organic system that followed the guidelines of the Organic Farmers Association of New Jersey. No significant differences were observed in either the high input or low input system despite a reduction in synthetic pesticide and fertilizer use. Organically produced tomatoes yielded significantly less than the other production systems in terms of total yields. Average fruit size was increased, however, along with the percentage of tomatoes with diameters larger than 7.7 cm. Differences in pest populations were noted between the plots.