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Accurate carbon and water flux simulations for croplands are greatly dependent on high quality representation of management practices and meteorological conditions, which are key drivers of the surface-atmosphere exchange processes. Fourteen site-years of carbon and water fluxes were simulated using the CropSyst model over four agricultural sites in the inland Pacific Northwest (iPNW) US from October 1, 2011 to September 30, 2015. Model performance for field-scale net ecosystem exchange of CO2 (NEE) and evapotranspiration (ET) was evaluated by comparing simulations with long-term eddy covariance measurements. The model captured the temporal variations of NEE and ET reasonably well with an overall r of 0.78 and 0.80, and a low RMSE of 1.82 g C m−2 d−1 and 0.84 mm d−1 for NEE and ET, respectively. The model slightly underestimated NEE and ET by 0.51 g C m−2 d−1 and 0.09 mm d−1, respectively. ET simulations showed better agreement with eddy covariance measurements than NEE. The model performed much better for the sites with detailed initial conditions (e.g., SOC content) and management practice information (e.g., tillage type). The CropSyst results showed that the winter wheat fields could be annual net carbon sinks or close to neutral with the net ecosystem carbon balance (NECB) ranging from 92 to −17 g C m−2, while the spring crop fields were net carbon sources or neutral with an annual NECB of −327 to −3 g C m−2. Simulations for the paired tillage sites showed that the no-till site resulted in lower CO2 emissions for the crop rotations of winter wheat-spring garbanzo, but had higher carbon loss into the atmosphere for spring canola compared to the conventional tillage site. Water budgets did not differ significantly between the two tillage systems. Winter wheat in the high-rainfall area had higher crop yields and water use efficiency but emitted larger amounts of CO2 into the atmosphere than in the low-rainfall area. Based on model evaluations in this study, CropSyst appears promising as a tool to simulate field-scale carbon and water budgets and assess the effects of different management practices and local meteorological conditions for the wheat-based cropping systems in this region.

Heavy application of nitrogen (N) fertilizers to agroecosystems contributes to water pollution and emission of nitrous oxide (N2O), an atmospheric constituent implicated in the greenhouse effect and stratospheric ozone depletion. The incorporation of cover crops biomass into agricultural soil is a practice that could provide a portion of the N needed by growing crops, and thereby could help reduce N fertilizer input and N loss from agroecosystems. Although the cover crop composition and the tillage management history of receiving soils could affect the pattern of mineral N release and its fates, these questions have not been addressed in previous research. A greenhouse experiment (85 d) was conducted to investigate the effects of two cover crops, hairy vetch (Vicia villosa, C/N: 11) and rye (Secale cereale, C/N: 82) on mineral N flux, N2O emission, and corn growth in soils under no-till (NT, 11 years) and plow-till (PT). Overall, tillage practice had only a marginal influence on N dynamics. Although NO3- flux was enhanced by both cover crops, the NO3- released was more efficiently utilized in the rye treatment. Corn growth and N uptake were significantly greater (P

Jabran, Khawar/0000-0001-8512-3330; Farooq, Shahid/0000-0002-6349-1404; Farooq, Muhammad/0000-0003-4368-9357 WOS: 000413649700051 PubMed: 28913583 Wheat productivity and profitability is low under conventional tillage systems as they increase the production cost, soil compaction, and the weed infestation. Conservation tillage could be a pragmatic option to sustain the wheat productivity and enhance the profitability on long term basis. This study was aimed to evaluate the economics of different wheat-based cropping systems viz. fallow-wheat, rice-wheat, cotton-wheat, mung bean-wheat, and sorghum-wheat, with zero tillage, conventional tillage, deep tillage, bed sowing (60/30 cm beds and four rows), and bed sowing (90/45 cm beds and six rows). Results indicated that the bed sown wheat had the maximum production cost than other tillage systems. Although both bed sowing treatments incurred the highest production cost, they generated the highest net benefits and benefit: cost ratio (BCR). Rice-wheat cropping system with bed sown wheat (90/45 cm beds with six rows) had the highest net income (4129.7 US$ ha(-1)), BCR (2.87), and marginal rate of return compared with rest of the cropping systems. In contrast, fallow-wheat cropping system incurred the lowest input cost, but had the least economic return. In crux, rice-wheat cropping system with bed sown wheat (90/45 cm beds with six rows) was the best option for getting the higher economic returns. Moreover, double cropping systems within a year are more profitable than sole planting of wheat under all tillage practices. Higher Education Commission of PakistanHigher Education Commission of Pakistan Authors are grateful to Higher Education Commission of Pakistan for financial support for this study.

Field experiments were conducted to examine the effect of tillage practices on sediment and nutrient loss and soybean growth under natural rainfall conditions. Three tillage practices were applied: downslope ridge (check) ,downslope ridge + contour living hedgerow,and cross ridge. Cross ridge tillage reduced surface runoff by 69% and sediment yield by 86% ,compared to the check treatment. The downslope ridge with a contour living hedgerow reduced surface runoff by 24% and sediment yield by 53% . Additionally,compared to the check plot ,nutrient losses carried by runoff were reduced by over 68% and that carried in the sediment was reduced more than 85% in the cross ridge plot. Nutrient losses in runoff were reduced by 20% to 30% in the downslope ridge and contour living hedgerow plot and those carried in the sediment were reduced by 44% to 57% . Cross ridge tillage soybean yields exceeded those of the downslope ridge and downslope ridge + contour living hedgerow treatments by 16% – 18% . Cross ridge tillage could contribute to the prevention sediment and nutrient loss and could improve crop yield, and thus it is recommended to be applied to mild slopes in the red soil region.

Jabran, Khawar/0000-0001-8512-3330; Farooq, Muhammad/0000-0003-4368-9357; WOS: 000383826400022 Crop rotation and tillage systems have important implications for weed infestation and crop productivity. In this study, five tillage systems viz. zero tillage (ZT), conventional tillage (CT), deep tillage (DT), bed sowing (60/30 cm with four rows; BS1) and bed sowing (90/45 cm with six rows; BS2) were evaluated in five different crop rotations viz. fallow-wheat (FW), rice-wheat (RW), cotton-wheat (CW), mungbean-wheat (MW) and sorghum-wheat (SW) for their effect on weed infestation and productivity of bread wheat. Interaction between different tillage practices and cropping systems had significant effect on density and dry biomass of total, broadleaved and grass weeds, agronomic and yield-related traits, and grain yield of bread wheat. The un-disturbed soils (ZT) under fallow-wheat or mungbean-wheat rotations favoured the weed prevalence (a total weed dry biomass of 72.4-109.6 and 105.6-112.1 g m(-2) in first and second year, respectively). Contrary to this, the disturbed soils (CT, DT, BSI and BS2) had less weed infestation with either of the rotations (a total weed biomass of 0.4-7.1 and 1.1-5.4 g m(-2) in first and second year, respectively). Sorghum-wheat rotation had strong suppressive effect on weed infestation in all tillage systems. The impact of crop rotation was more visible during second year of experimentation. Bed sown wheat (BS1 and BS2) in mungbean-wheat rotation had the highest wheat grain yield (6.30-6.47 t ha(-1)) compared to other tillage systems in different crop rotation combinations. (C) 2016 Elsevier Ltd. All rights reserved. Higher Education Commission of PakistanHigher Education Commission of Pakistan Authors are grateful to Higher Education Commission of Pakistan for financial support to accomplish this research project.

National audience

In the past several decades, agricultural management practices consisting of intensive tillage and high rate of fertilization to improve crop yields have resulted in the degradation of soil and environmental qualities by increasing erosion and nutrient leaching in the groundwater and releasing greenhouses gases, such as carbon dioxide (CO2) and nitrous oxide (N2O), that cause global warming in the atmosphere by oxidation of soil organic matter. Consequently, management practices that sustain crop yields and improve soil and environmental qualities are needed. This paper reviews the findings of the effects of tillage practices, cover crops, and nitrogen (N) fertilization rates on crop yields, soil organic carbon (C) and N concentrations, and nitrate (NO3)-N leaching from the soil. Studies indicate that conservation tillage, such as no-till or reduced till, can increase soil organic C and N concentrations at 0- to 20-cm depth by as much as 7–17% in 8 years compared with conventional tillage without significantly altering crop yields. Similarly, cover cropping and 80–180 kg N ha–1year–1fertilization can increase soil organic C and N concentrations by as much as 4–12% compared with no cover cropping or N fertilization by increasing plant biomass and amount of C and N inputs to the soil. Reduced till, cover cropping, and decreased rate of N fertilization can reduce soil N leaching compared with conventional till, no cover cropping, and full rate of N fertilization. Management practices consisting of combinations of conservation tillage, mixture of legume and nonlegume cover crops, and reduced rate of N fertilization have the potentials for sustaining crop yields, increasing soil C and N storage, and reducing soil N leaching, thereby helping to improve soil and water qualities. Economical and social analyses of such practices are needed to find whether they are cost effective and acceptable to the farmers.

International audience; Soil mixing and the downward movement of solid matter in soils are dynamic pedological processes that strongly affect the vertical distribution of all soil properties across the soil profile. These processes are affected by land use and the implementation of various farming practices, but their kinetics have rarely been quantified. Our objective was to investigate the vertical transfer of matter in Luvisols at long-term experimental sites under different land uses (cropland, grassland and forest) and different farming practices (conventional tillage, reduced tillage and no tillage). To investigate these processes, the vertical radionuclide distributions of Cs-137 and Pb-210 (xs) were analyzed in 9 soil profiles. The mass balance calculations showed that as much as 91 +/- 9% of the Cs-137 was linked to the fine particles (

We conducted a 3-year field experiment on an Anthrosol paddy soil to investigate changes in crop yield, P uptake and soil organic phosphorus (P) fractions after 3 years of conventional tillage (CT) conversion to no-tillage (NT) under a rape - rice rotation in central China. Treatments were established following a split-plot design of a randomized complete block with tillage practice as the main plot and fertilizer as the sub-plot treatment. The yields of rape and rice ranged from 1378 to 2264 kg ha-1 and from 5895 to 9453 kg ha-1 across 3 years, respectively. Moreover, P uptake for rape and rice (aboveground) varied from 3.9 to 10.4 kg ha-1 and from 9.5 to 32.0 kg ha-1, respectively. Fertilization significantly enhanced crop yields and P uptake, but tillage did not affect the yields and P uptake. Fertilization significantly increased total P concentrations, acid phosphatase activity, Bray-1 P and labile organic P in the 0-5 cm soil layer. Compared to the CT treatments, the NT treatments had significantly higher acid phosphatase activity, total P, Bray-1 P, total organic P and organic P fractions in the 0-5 cm soil layer but lower organic P fractions in the 5-20 cm soil layer. Therefore, our results suggest that short-term NT does not enhance organic P concentrations in the 0-20 cm soil layer, and only improve P availability on the soil surface.

Effects of six tillage practices on saturated hydraulic conductivity (HC), soil bulk density (BD), and penetrationresistance (PR) were evaluated for a clayey soil (Typic Haploxererts) under semi-arid Mediterranean conditions ina three year study (2006-2009). The experiment was conducted on a randomized complete block design with threereplicates. Treatments were: conventional tillage with residue incorporated (CTS), conventional tillage with residueburned (CTB), reduced tillage with heavy tandem disc harrow (RTD), reduced tillage with rotary tiller (RTR),reduced tillage with heavy tandem disc harrow for the first crop + no-tillage for the second crop (RNT), and notillage (NT). The study was conducted in wheat-corn, wheat-soybean and wheat crop rotations. The tillage effectson HC, BD and PR were significant at soil depth of 0-30 cm. The hydraulic conductivity was higher in CTS, andfollowed by CTB, RTR, RTD, RNT and NT practices, respectively. The hydraulic conductivity values under NT in2007 and 2008 were 20% and 30% lower at 0-30 cm depth compared with CTS, respectively. The conventionaltillage treatments in the semi-arid conditions improved the HC with decreasing BD and PR of the clayey soil. TheBD and PR values were higher under NT treatments than the tilled plots and increased with depth. The values ofsoil compaction indicators were significantly greater under no-tillage and reduced tillage as compared to thoseunder conventional tillage in all soil depths studied., Altı farklı toprak işleme yönteminin üç yıllık sürede (2006–2009) yarı-kurak Akdeniz iklim koşullarında killi bir toprakta (Typic Haploxererts) doymuş hidrolik iletkenlik, hacim ağırlığı ve penetrasyon direncine etkileri değerlendirilmiştir. Araştırma tesadüf parseller desenine göre üç tekerrürlü olarak yürütülmüştür. Toprak işleme uygulamaları olarak: Anızlı geleneksel toprak işleme (CTS), anızları yakılmış geleneksel toprak işleme (CTB), ağır diskli tırmıklı azaltılmış toprak işleme (RTD), rototillerli azaltılmış toprak işleme (RTR), birinci ürün için ağır diskli tırmıklı azaltılmış işleme + ikinci ürün için sıfır toprak işleme (RNT) ve sıfır toprak işleme (NT) yöntemleri kullanılmıştır. Araştırmada buğday-mısır, buğday-soya ve buğday rotasyonu uygulanmıştır. Toprak işleme uygulamalarının farklı derinliklerde doymuş hidrolik iletkenlik, hacim ağırlığı ve penetrasyon dirençleri ölçülmüştür. Toprak işleme uygulamalarının 0–30 cm toprak derinliğinde hidrolik iletkenlik, hacim ağırlığı ve penetrasyon direncine önemli etkileri belirlenmiştir. Hidrolik iletkenlik en yüksek CTS altında belirlenmiş ve bunu sırasıyla CTB, RTR, RTD, RNT ve NT izlemiştir. 2007 ve 2008 yılında 0–30 cm derinlikteki hidrolik iletkenli değerleri, NT uygulamalarında CTS’e göre sırasıyla %20 ve %30 daha düşük bulunmuştur. Geleneksel toprak işleme uygulamaları yarı-kurak iklim koşullarında hacim ağırlığını ve penetrasyon direncini azaltarak hidrolik iletkenliği arttırmıştır. NT uygulamasında elde edilen hacim ağırlığı ve penetrasyon direnç değerleri işlenen topraklara göre daha yüksek bulunmuş ve bu değerler derinlikle birlikte artmıştır. Toprak sıkışmasının göstergeleri olan değerler işlenmeyen ve azaltılmış işleme uygulamaları altında geleneksel işleme uygulamalarına göre bütün derinliklerde önemli ölçüde yüksek bulunmuştur.

Effects of six tillage practices on some soil microbiological properties and crop yields were evaluated for a clay soil (Typic Haploxererts) under semi-arid Mediterranean conditions in a three year study (2006-2009). The experiment was designed as a completely randomized-block with three replications. Treatments were: conventional tillage with residue incorporated (CT1), conventional tillage with residue burned (CT2), reduced tillage with heavy tandem disc harrow (RT1), reduced tillage with rotary tiller (RT2), reduced tillage with heavy tandem disc harrow for the first crop + no-tillage for the second crop (RNT), and no tillage (NT). The study was conducted in wheat-corn, wheat-soybean and wheat crop rotations. Dehydrogenase activity, soil respiration, mycorrhizal spore number, total organic carbon (TOC), and total N were determined at three depths (0-10, 10-20 and 20-30 cm). The mycorrhizal spore number responded quite early to tillage practices. Significant tillage effects on TOC and total N were observed only at 0-10 cm depth. The TOC content was increased by NT, RT2, RNT and RT1 practices compared to the initial values at the same depth as 74%, 62%, 56%, and 50%, respectively. Dehydrogenase activity (DHA) and soil respiration were higher on the surface and decreased with depth. Reduced and no-tillage practices significantly increased the mycorrhizal spore number, dehydrogenase activity and soil respiration at all depths (P

Effects of six tillage practices on saturated hydraulic conductivity (HC), soil bulk density (BD), and penetration resistance (PR) were evaluated for a clayey soil (Typic Haploxererts) under semi-arid Mediterranean conditions in a three year study (2006-2009). The experiment was conducted on a randomized complete block design with three replicates. Treatments were: conventional tillage with residue incorporated (CTS), conventional tillage with residue burned (CTB), reduced tillage with heavy tandem disc harrow (RTD), reduced tillage with rotary tiller (RTR), reduced tillage with heavy tandem disc harrow for the first crop + no-tillage for the second crop (RNT), and no tillage (NT). The study was conducted in wheat-corn, wheat-soybean and wheat crop rotations. The tillage effects on HC, BD and PR were significant at soil depth of 0-30 cm. The hydraulic conductivity was higher in CTS, and followed by CTB, RTR, RTD, RNT and NT practices, respectively. The hydraulic conductivity values under NT in 2007 and 2008 were 20% and 30% lower at 0-30 cm depth compared with CTS, respectively. The conventional tillage treatments in the semi-arid conditions improved the HC with decreasing BD and PR of the clayey soil. The BD and PR values were higher under NT treatments than the tilled plots and increased with depth. The values of soil compaction indicators were significantly greater under no-tillage and reduced tillage as compared to those under conventional tillage in all soil depths studied. © Ankara Üniversitesi Ziraat Fakültesi.

Tillage information is crucial for environmental modeling as it directly affects evapotranspiration, infiltration, runoff, carbon sequestration, and soil losses due to wind and water erosion from agricultural fields. However, collecting this information can be time consuming and costly. Remote sensing approaches are promising for rapid collection of tillage information on individual fields over large areas. Numerous regression-based models are available to derive tillage information from remote sensing data. However, these models require information about the complex nature of underlying watershed characteristics and processes. Unlike regression-based models, Artificial Neural Network (ANN) provides an efficient alternative to map complex nonlinear relationships between an input and output datasets without requiring a detailed knowledge of underlying physical relationships. Limited or no information currently exist quantifying ability of ANN models to identify contrasting tillage practices from remote sensing data. In this study, a set of Landsat TM-based ANN models was developed to identify contrasting tillage practices in the Texas High Plains. Observed tillage data from Moore and Ochiltree Counties were used to develop and evaluate the models, respectively. The overall classification accuracy for the 15 models developed with the Moore County dataset varied from 74% to 91%. Statistical evaluation of these models against the Ochiltree County dataset produced results with an overall classification accuracy varied from 66% to 80%. The ANN models based on TM band 5 or indices of TM Band 5 may provide consistent and accurate tillage information when applied to the Texas High Plains. � 2010 by the authors; licensee Molecular Diversity Preservation International, Basel, Switzerland.

This thesis is divided into two main components. For the first component, the first objective of the study was to compare the NH4 + concentrations measured by standard salicylate- and phenol-based methods using a set of soil samples obtained from a single-site manure application study. The second objective was to assess the use of water instead of KCI as the carrier in both methods. Therefore, for analysis of soil-extracted NH4+-N at low concentrations (below 1 mg NH 4+-N L-1), the salicylate-based method can be used effectively with water as a carrier instead of KCI. For the second component of this thesis, pathways of nitrogen (N) loss were quantified at two study sites with two consecutive spring manure applications at Elora, Ontario and a single fall manure application at Ridgetown, Ontario. Treatments consisted of: a control where no manure was applied and no tillage practice, surface application without tillage, pre-tillage, incorporation and a combination of pre-tillage and incorporation. Nitrogen measurements included NH3 volatilization following application and NH4 +-N and NO3--N content in water samples for the remainder of the application year. Water samples were taken from overland flow, lysimeters, tile drains, and groundwater. The first three sources of water were monitored for concentration and total flow volume from which total annual and seasonal mass loadings were calculated. Groundwater NH4+-N and NO3--N concentrations only were determined. In addition to water samples, soil samples were taken before manure application and after harvest. At harvest, grain and stover samples were obtained for measurement of biomass and analyzed for N content. The 2007 growing season had lower than normal precipitation and 2008 had higher than normal precipitation. Volume of water showed a higher influence than N concentration for N loading results from overland flow, water captured in lysimeters, and tile drains. Few treatment differences were found and water sample data was inconclusive regarding tillage practice. Grain yield and grain N content favoured the pre-tillage and incorporation treatment while surface applied was the least beneficial. NH3 volatilization comparison also favoured the combination tillage treatment. Groundwater nitrate-N concentration averages at Elora stayed below the 10 mg L-1 drinking water standard, whereas at Ridgetown they were often 2 or 3 times higher than the limit.

Conventional drainage systems tend to aggravate runoff and nutrient leaching problems on farms especially during the off-season. This study uses a biophysical economic model to identify, evaluate and determine multifunctional benefits of implementing and establishing nitrogen rate fertilizer application and conservation tillage practices as best management practices (BMPs) in the lower Mississippi River Basin (MRB). Simulation results showed that agricultural producers generally preferred no tillage to conventional tillage in reducing nutrient runoffs from fields because of higher net revenue per acre. Finally, given nitrogen runoff restrictions, farmers reduced crop acreage and nitrogen fertilizer application rates to help minimize losses.

Conservation Agriculture (CA) has been practised for three decades and has spread widely. We estimate that there are now some 106 million ha of arable and permanent crops grown without tillage in CA systems, corresponding to an annual rate of increase globally since 1990 of 5.3 million ha. Wherever CA has been adopted it appears to have had both agricultural and environmental benefits. Yet CA represents a fundamental change in production system thinking. It has counterintuitive and often unrecognized elements that promote soil health, productive capacity and ecosystem services. The practice of CA thus requires a deeper understanding of its ecological underpinnings in order to manage its various elements for sustainable intensification, where the aim is to optimize resource use and protect or enhance ecosystem processes in space and time over the long term. For these reasons CA is knowledge-intensive. CA constitutes principles and practices that can make a major contribution to sustainable production inten...

Corn ('Zea mays' L.), a major grain crop in Ontario, Canada, is grown using varied crop rotations and tillage systems. Corn growth and yield varies across these production systems and it is hypothesized that yield differences are, in part, due to direct effects of soil aggregate size distribution, and/or indirectly, by affecting other soil characteristics such as availability of nutrients, water, oxygen, and soil temperature. To evaluate the effect of aggregates on early corn growth, a series of experiments were carried out with objectives; (1) to evaluate the effect of crop rotation and tillage practices on soil aggregate distribution, and its relationship to corn biomass production; (2) to characterize corn root morphological responses to aggregate size under conditions where indirect effects of aggregates are removed; and (3) to determine possible mechanisms involved in corn response to aggregates. In a field experiment, rotation and tillage system independently affected corn dry matter production. In soils of continuous corn, 54% to 59% of the soil mass occurred in the largest aggregate size class (>8mm) at planting and this was significantly higher when compared to soils of other rotations. Corn plant biomass was negatively correlated to the percentage of >8mm soil aggregates [r=-0.34 (p=0.009) and r=-0.79 (

In recent years agricultural research has developed field practices that promote soil conservation, but how widely are such practices used in Canada? This question has been difficult to answer because no comprehensive inventory of these practices was available. To remedy this, Agriculture and Agri-Food Canada's Centre for Land and Biological Resources Research and the Prairie Farm Rehabilitation Administration (PFRA) worked with the Agricultural Division of Statistics Canada to design a new land management module for the Canada Census of Agriculture. This module was first introduced in the 1991 Census, and results are presented in this report. The objectives of this report are: to record how agricultural land is used and managed in Canada, to produce a study that will serve as a baseline for all subsequent monitoring of land management practices through the census, and to provide information useful for environmental studies of soil and water quality.

This report contains an evaluation of the costs and returns associated with a range of conventional and conservational tillage practices demonstrated in the Tillage 2000 program. The analysis incorporated results from 1986 to 1989 for corn, soybeans, wheat and spring grains produced in southwestern Ontario. The major findings of this study are two-fold: 1. No-till and reduced tillage practices are financially competitive with conventional tillage practices in corn and winter wheat but less competitive in soybeans and spring grains. 2. No-till provides producers with potential for significant labour savings and equipment cost savings when used in corn. Specifically, the net returns per hour are significantly higher than either conventional or reduced tillage practices. This means that no-till cropping operations would be most valuable on farms with high opportunity costs to labour. Agriculture Canada

The purpose of the workshop is to explore current concerns regarding nitrate and associated compounds used in agriculture, to examine their effects on water quality conditions and measures required to minimize impacts. The intent is to share information and to make recommendations relevant to water management research and services in the agricultural industry. The workshop will provide a forum for engineers, scientists, farmers, suppliers, managers and operators involved in the field of research, development, application and management of nitrate in agriculture.

Average per-acre returns differ little for most U.S. corn and soybean farmers using various alternative tillage strategies, according to this analysis of 1980 farm-level production data. Midwest conventional-till soybean farmers, however, accrue a significantly higher average return than do Midwest no-till farmers. Most conservation-till soybean farmers in the three major producing regions incur significantly lower input costs than do conventional-till soybean farmers, but also harvest lower yields except in the Southeast. Significant differences were found in the use of specific corn and soybean inputs among alternative tillage strategies

This article 'Insect-Suppressing Effect of Rice Stubble Height, Tillage Practices, and Straw Mulch in a Wetland Rice-Cowpea Cropping Pattern' appeared in the International Rice Research Newsletter series, created by the International Rice Research Institute (IRRI). The primary objective of this publication was to expedite communication among scientists concerned with the development of improved technology for rice and for rice based cropping systems. This publication will report what scientists are doing to increase the production of rice in as much as this crop feeds the most densely populated and land scarce nations in the world.

The objectives of this study were as follows: 1) to develop a method to inventory the nature and extent of implementation of soil and water conservation practices on farmland in eleven counties in Southwestern Ontario, 2) to compile the resultant data into an inventory of cropping, tillage, and land management practices being conducted in the study area at this point in time (1984).

Pesticide use varies considerably by crop, according to the Economic Research Service's 1982 Crop and Livestock Pesticide Usage Survey. Eleven percent of farmers who responded used professional scouting for pest problems, 59 percent self scouted their fields, and 12 percent were aware of beneficial insects and diseases. The extent of no- or reduced-till systems varied by crop. Almost 70 percent of the farmers with livestock used insecticides for livestock insect control. A majority of the respondents used common pesticide application safety equipment and 15 percent used specialized safety equipment.

This article 'A Test of Tillage Practices in Thailand' appeared in the International Rice Research Newsletter series, created by the International Rice Research Institute (IRRI). The primary objective of this publication was to expedite communication among scientists concerned with the development of improved technology for rice and for rice based cropping systems. This publication will report what scientists are doing to increase the production of rice in as much as this crop feeds the most densely populated and land scarce nations in the world.

A simulation model with time-dependent hydraulic conductivity parameters was used to predict the effects of three different tillage practices: conventional tillage (CT), no-tillage (NT) and subsoiling tillage (ST) on the components of the soil water balance during the summer maize growing season. The predictive capability of the model was improved, particularly for the subsoiling tillage case. The simulation results show that temporal changes in soil hydraulic conductivity induced by different tillage practices can affect percolation, water storage, transpiration and evaporation. Differences in the simulated components of the water balance were found to be small between CT and NT practices, but larger in the ST case. Compared with the conventional and no-tillage methods, subsoiling promotes infiltration and deep percolation, thereby favoring a possible recharge of the groundwater. Actual evaporation is always lower in the subsoiled plots, whatever the hydrological year. Transpiration is similar for the three treatments, suggesting no significant differences in water availability, except in wet years where it is higher in subsoiled soils.