E. J. Kladivko

Tillage systems and soil ecology

Tillage systems affect the soil physical and chemical environment in which soil organisms live, thereby affecting soil organisms. Tillage practices change soil water content, temperature, aeration, and the degree of mixing of crop residues within the soil matrix. These changes in the physical environment and the food supply of the organisms affect different groups of organisms in different ways. One of the challenges of research in soil ecology is to understand the impacts of management on the complex interactions of all organisms at the soil community level. In addition to the response of organisms to soil manipulations, agriculturalists are interested in the actions of soil organisms on the physical and chemical environment in the soil. Soil organisms perform important functions in soil, including structure improvement, nutrient cycling, and organic matter decomposition. This paper discusses the effects of tillage practices on soil organism populations, functions, and interactions. Although there is a wide range of responses among different species, most organism groups have greater abundance or biomass in no-till than in conventional tillage systems. Larger organisms in general appear to be more sensitive to tillage operations than smaller organisms, due to the physical disruption of the soil, burial of crop residue, and the change in soil water and temperature resulting from residue incorporation. Variations in responses found in different studies reflect different magnitudes of tillage disruption and residue burial, timing of the tillage operations, timing of the measurements, and different soil, crop, and climate combinations. The paper concludes with a discussion of challenges for tillage researchers.

Pesticide Transport to Subsurface Tile Drains in Humid Regions of North America

This report reviews and summarizes findings from more than 30 North American studies of pesticide transport into subsurface agricultural drains. Background information about subsurface drainage use and its importance for crop production and environmental protection is also presented. The presence of a subsurface drainage system generally increases the volume of infiltration and consequently decreases the volume of surface runoff water and sediment compared with similar soils where subsurface drainage systems are not installed. Therefore, in general, the presence of subsurface drainage decreases surface runoff losses of sorbed compounds such as pesticides, both because of lower runoff volumes and often also because of lower concentrations in the runoff resulting from the delayed initiation of runoff. Pesticide concentrations and mass losses are usually much lower in subsurface drainage than in surface runoff, often by an order of magnitude. In the medium- and fine-textured soils where subsurface drainage is common, the dominant mechanism for pesticide transport to the drain tiles is most likely preferential flow during rainfall/drainage events occurring soon after pesticide application. Concentrations and mass losses in subsurface drains are highly variable from year to year, depending on weather patterns.

Earthworms and rate of breakdown of soybean and maize residues in soil

Abstract A field survey was conducted to determine the numbers and biomass of earthworms in soils receiving different tillage and cropping treatments, and to investigate in a greenhouse study the effect of earthworms on the rate of breakdown of soybean ( Glycine max ) and maize ( Zea mays L.) residues. The numbers and biomass of earthworms under continuous soybeans were greater than those present under maize, possibly due to the adverse effects of insecticide and anhydrous ammonia fertilizer used with maize. No-tillage doubled the population of earthworms under soybeans, when compared with ploughing. Numbers (141 m −2 ) and biomass (26.5 g m −2 ) of earthworms under no-till soybeans were still much lower than the numbers (1298 m −2 ) and biomass (224.5 g m −2 ) under pasture receiving heavy applications of animal manure. Using 16-1 pots in the greenhouse, the effect of 0, 15 (250m −2 ) and 30 (500m −2 ) earthworms ( Lumbricus rubellus ) pot −1 on the rate of breakdown during 54 days of 50 g of soybean or maize residues in the Raub silt loam (Aquic Argiudoll) was studied. At 36 days, 60% of the soybean residues were recovered from pots to which no earthworms had been added, whereas in the presence of earthworms, only 34% of the soybean residues remained. In the absence of earthworms, 85% of the maize residues were recovered at 36 days, compared with only 52% in the presence of earthworms. At 36 days, 48% of the original maize residues added were still > 2 mm in length in the absence of earthworms, whereas only 26% were > 2 mm in length in the presence of earthworms. Earthworms also increased the aggregate stability of the Raub soil, when determined on moist (19–22% w/w) samples, but had no effect on soil water retention at −33 and −1500 kPa. The possible implications of greater earthworm activity on increasing residue incorporation and breakdown and subsequent effects on soil temperatures under no-till maize production are also discussed.

Soil macroporosity, hydraulic conductivity and air permeability of silty soils under long-term conservation tillage in Indiana

With the increasing use of conservation tillage, many questions about the long-term effects of tillage system on soil physical properties have been raised. Studies were conducted to evaluate saturated hydraulic conductivity (KSAT), macropore characteristics and air permeability of two silty soils as affected by long-term conservation tillage systems in the state of Indiana. Measurements were taken during the tenth year of a tillage study on a Chalmers silty clay loam (Typic Haplaquoll) and the fifth year of a study on a Clermont silt loam (Typic Ochraqualf). Tillage systems were moldboard plow, chisel, ridge till-plant, and no-till in a rotation of corn (Zea mays L.) and soya beans (Glycine max L.). Saturated hydraulic conductivity was measured on large soil columns (25 × 25 × 40 cm) before spring tillage, and macropore size and continuity were assessed with staining techniques. Intact soil cores (8 cm diam × 10 cm) were collected in early July in the row and non-trafficked interrow at three depths (10–20, 20–30, and 30–40 cm) and were analyzed for air permeability (Kair), air-filled porosity and bulk density. Saturated hydraulic conductivity values were in the order plow > chisel > ridge till > no-till for the Chalmers soil and were significantly greater in the plow treatment than in the other 3 tillage systems on the Clermont soil. Differences in KSAT between the 2 soils were generally greater than differences among tillage systems, and coefficients of variation were lower for treatments that did not include may fall tillage operations. At the 10-cm depth on the Chalmers soil, the chisel treatment had the greatest number of stained cylindrical channels, whereas for the Clermont soil the ridge till had the greatest number at this depth. Although the no-till treatment had similar or fewer total channels, it had the most continuous channels from the 10-cm depth to the 20- and 30-cm depths on both soils. Tillage system, row position and depth all affected Kair. On the Chalmers soil, plow, chisel and ridge systems had lower Kair between rows than in the row at the 10–20-cm depth, whereas no-till had constant Kair in the row and between the row. On the Clermont soil, ridge till had the highest Kair of all treatments at the 10–20-cm depth, and no-till had the highest Kair of all treatments at the 20–30-cm depth.

Conservation tillage effects on soil properties and yield of corn and soya beans in Indiana

Long-term studies have been conducted on 7 soils throughout the state of Indiana, to determined the effectiveness of a range of tillage systems in producing high crop yields while reducing erosion and improving soil physical properties. The soil studied included one sandy loam, one loam, three silt loams and two silty clay loams with a range of organic matter contents and slope and drainage classes. Tillage systems studied included conventional moldboard plow, chisel plow, disking, ridge till-plant and no-till. Conservation tillage systems resulted in higher soil water contents, lower soil temperatures, more organic matter and more water-stable aggregates near the surface, and higher bulk densities than conventional tillage systems. On sloping, well-drained, low organic matter soils, conservation tillage produced corn (Zea mays L.) yields that were equal or better than yields from conventional tillage. On poorly-drained, low organic matter, poorly structured soils, the soil structure under conservation tillage tended to improve with time as soil organic matter and aggregation increased. Corn and soya bean (Glycine max) yields have also improved with time and often exceed those from conventionally tilled soils. On poorly drained soils high in organic matter that were cropped to continuous corn, conservation tillage generally yielded less than conventional systems due to low soil temperature and excess wetness in spring. Significant interactions of tillage systems and crop rotation existed on the two poorly-drained soils on which rotation was an experimental variable.

Characterization of soil temperature, water content, and maize root distribution in two tillage systems

Abstract Previous research has shown that soil temperature and soil water regimes are influenced by tillage practices. Root growth is affected by both soil temperature and water content; therefore, root distribution can be significantly different among various tillage systems. The objectives of this field study were to characterize the distribution of maize (Zea mays L.) roots in the top 30 cm of the profile of a Chalmers silty clay loam soil (Typic Haplaquoll) under a ridge till-plant system and a conventional tillage system and to determine if any significant differences exist among soil temperature and water regimes in these two tillage systems and if these differences were related to maize root distribution. Measurements were taken over a 3 year period on three replicates of a long-term tillage experiment. Soil cores (2.1 cm diameter) were taken after approximately 5, 7, and 10 weeks of growth to determine root length density with depth and distance from the row. Soil temperature was measured with thermocouples at depths of 2.5, 10, and 30 cm in the row and midrow. Soil water content was determined gravimetrically on samples taken two to three times per week from the row and midrow. Root length density (RLD) was higher in the row and midrow in the ridge till treatments; whereas in the conventional treatments, RLD was highest in the row and decreased with distance from the row. Mean 24 h temperatures in the row of ridge till treatments paralleled those in the row of conventional treatments. Midrow temperatures tended to be lower in ridge till than in conventional treatments, especially during the 3 week period after planting. Water content in the row of both tillage treatments was similar from planting to midsilk in both years. Water content in the midrow of ridge till was greater than that of conventional treatments throughout the sampling period. No significant correlations between RLD and soil temperature or water content were found; however, significant differences in soil temperature, water content, and RLD between the two tillage treatments suggest that some relationship does exist.

Impacts of drainage water management on subsurface drain flow, nitrate concentration, and nitrate loads in Indiana

Drainage water management is a conservation practice that has the potential to reduce drainage outflow and nitrate (NO3) loss from agricultural fields while maintaining or improving crop yields. The goal of this study was to quantify the impact of drainage water management on drain flow, NO3 concentration, and NO3 load from subsurface drainage on two farms in Indiana. Paired field studies were conducted following the paired watershed statistical approach modified to accommodate autocorrelation. Annual NO3 load reductions ranged from 15% to 31%, with an overall reduction of 18% to 23% over the 2-year period, resulting from reductions in both flow and NO3 concentration. Although the study revealed weaknesses in using the paired statistical approach for a dynamic practice like drainage water management, the results of this study support the use of drainage water management as a conservation practice and provide information for decision-makers about the level of benefits that can be anticipated.

Seasonal variations in infiltration rate under no-till and conventional (disk) tillage systems as affected by Lumbricus terrestris activity

Abstract Lumbricus terrestris activity can improve water flow into soils, but the effects of L. terrestris (nightcrawlers) on infiltration and runoff rates throughout the growing season have not been quantified. Our objective was to quantify and describe the effects of L. terrestris on infiltration rates under an established no-till and a disk tillage system on a silt loam Alfisol (fine-loamy, mixed, mesic Aquollic Hapludalf) in west central Indiana. Under each tillage practice there were areas within the field that had L. terrestris activity and other areas that had no activity, as indicated by the presence or absence, respectively, of middens. Infiltration was measured using a portable sprinkling infiltrometer which delivered 7 cm of water h−1 to a 1.4 m2 area. Infiltration was measured five times during the growing season, for the disk tillage treatment: (1) before any spring field work began; (2) immediately after tillage but before planting; (3) immediately after planting; (4) 3 weeks after planting; and (5) after harvest. For no-till treatments, the measurement times were the same as times 1, 3, 4, and 5 of the tilled site. Results showed that in early spring before any tillage was performed, the tilled treatment without middens had the highest infiltration rate and the tilled treatment with middens had the lowest. Immediately after planting and 3 weeks after planting, no-till with middens had the highest infiltration rates, but disk tillage treatments had the lowest infiltration rates. Measurements after harvest showed that no-till with middens again had the highest infiltration rates. The presence of L. terrestris, as indicated by the presence of middens, appears to have increased infiltration rates in a no-till system on this soil. In the disk system, however, the activity of L. terrestris and the presence of their middens apparently was not persistent enough to affect infiltration rates, and the amount of surface residue cover may be a more important factor in this system.

VALIDATING GLEAMS WITH PESTICIDE FIELD DATA ON A CLERMONT SILT LOAM SOIL

ABSTRACT The GLEAMS (Groundwater Loading Effects of Agricultural Management Systems) model was used to simulate the appearances of pesticides in outflow of an experimental drainage field at the South East Purdue Agricultural Center (SEPAC) in southeastern Indiana. This article presents the comparison of simulated and observed loading of Alachlor, Atrazine, Cyanazine, Carbofuran, and Chlorpyrifos in tile outflows for 1985 through 1989. The results of the simulation were close to field observations for total masses of pesticides leached from the root zone and for the overall timing of pesticide appearance in tile flows. However, the simulation of the watershed did not predict the observed arrival of pesticides in the drain during the first storm event after pesticide application. To compare the simulated results from on-site weather data and the data from nearby locations, long-term mean monthly solar radiation data for SEPAC and Indianapolis, Indiana were evaluated.

Field method for separating the contribution of surface‐connected preferential flow pathways from flow through the soil matrix

[1] Liquid latex was used as a method to seal visible surface-connected preferential flow pathways (PFPs) in the field in an effort to block large surface-connected preferential flow and force water to move through the soil matrix. The proposed approach allows for the quantification of the contribution of large surface-connected cracks and biological pores to infiltration at various soil moisture states. Experiments were conducted in a silty clay loam soil in a field under a no-till corn-soybean rotation planted to corn. Surface intake rates under ponding were measured using a simplified falling head technique under two scenarios: (1) natural soil conditions with unaltered PFPs and (2) similar soil conditions with latex-sealed large macropores at the surface. Results indicated that the contribution of flow from large surface-connected macropores to overall surface intake rates varied from approximately 34% to 99% depending on the initial moisture content and macroporosity present. However, evidence of preferential flow continued to appear in latex-sealed plots, suggesting significant contributions to preferential flow from smaller structural macropores, particularly in two out of four tests where no significant differences were observed between control and latex-sealed plots. Citation: Sanders, E. C., M. R. Abou Najm, R. H. Mohtar, E. Kladivko, and D. Schulze (2012), Field method for separating the contribution of surface-connected preferential flow pathways from flow through the soil matrix, Water Resour. Res., 48, W04534,