Conservation Tillage Treatments Research Articles

Tillage effects on energy use for corn silage in Mediterranean Coastal of Turkey

One of the main concepts of tillage should be to create the most appropriate soil conditions by taking into consideration energy use efficiency because it allows financial savings, fossil resources preservation and environment pollution decrease. Therefore, the study was perform to evaluate the effects of different tillage systems on energy use, the energy output/input ratios and profitability for silage corn ( Zea mays L) production. The tillage systems were consisted of conventional tillage without stubble (CT), minimum tillage (MT), band tillage (BT), ridge tillage (RT) and no-tillage (NT). The effects of tillage were found to be statistically on energy parameters. The highest energy use efficiency (8.78), energy productivity (2.12 kg MJ −1), and energy profitability (7.78) were in MT while the lowest in NT. But, the highest energy intensiveness was in NT (24.83 MJ EUR −1). Indirect energy, non-renewable energy and commercial energy shares were higher for all the systems. More renewable energy was used in NT than the other treatments. The highest benefit/cost ratio and productivity were in the MT (2.13), and followed by NT (2.07). For this reason, conservation tillage treatments (i.e. MT and NT) should be supported for the energy and profitability sustainability of corn silage agriculture.

Content of some elements in grain of spring wheat cv. Zebra depending on soil tillage systems and catch crop

The aim of the present study was to evaluate the effect of plough and conservation tillage treatment as well as various catch crops on the chemical composition of the grain of spring wheat grown in monoculture. The study was carried out in 2006 – 2008, using an experiment established in 2005. The experimental field was located on medium and heavy mixed rendzina soil. The design of a static two–factor experiment, set up using the split-plot method in four replications, included the plough tillage system (A) and two conservation tillage methods – with autumn (B) or spring (C) disking of catch crops. The other factor comprised four methods for regeneration of the spring wheat monoculture stand using the following catch crops: undersown red clover (b) and Westerwolds ryegrass (e); lacy phacelia (c) and white mustard stubble crops (d); and the control treatment without catch crops (a). The concentrations of potassium, manganese and sulphur in the spring wheat grain harvested from the ploughed plots were higher than in the conservation tillage treatment. In the plough tillage treatments, grain Mg content was higher than in the conservation tillage variant with spring disking of the catch crops. Conservation tillage had an effect on the increase in phosphorus and copper content in spring wheat grain compared to plough tillage. Zn and Fe content in the grain from the conservation tillage treatments with autumn disking of the catch crops was lower than in that from the plough and conservation tillage treatments with spring incorporation of the catch crops. Iron content in the grain obtained from the treatments with red clover and lacy phacelia was the highest. At the same time, phosphorus content in spring wheat grain was the highest in the control treatments and in the treatment with Westerwolds ryegrass and white mustard. In the plots where a lacy phacelia stubble crop had been sown, zinc and copper content in grain was determined to be the highest. In turn, the highest manganese content was found in the grain from the control treatments, whereas total sulphur content was the highest in the control plots and in the plots with the stubble crops.

Response of progeny bred from Bolivian and North American cultivars in integrated management systems for leaf spot of peanut ( Arachis hypogaea)

Early and late leaf spot (caused by Cercospora arachidicola and Cercosporidium personatum, respectively) are major yield-reducing diseases of peanut ( Arachis hypogaea L.) in the southeastern U.S. Effective suppression of both early and late leaf spot, collectively called ‘leaf spot’, can be reached with integrated disease management (IDM) systems utilizing peanut cultivars with moderate levels of resistance to these pathogens. A Bolivian landrace cultivar, Bayo Grande, and a series of progeny breeding lines were evaluated under two IDM systems consisting of various reduced application fungicide regimes and/or tillage treatments in field experiments over two years. In the absence of fungicides or when averaged across fungicide regimes, Bayo Grande and breeding lines had better leaf spot resistance when compared to cultivars Georgia Green, MDR-98 and C-99R in all experiments across years. The addition of three or four fungicide applications to Bayo Grande and several of the breeding lines suppressed leaf spot to levels similar to those genotypes and Georgia Green under the full regime. Conservation tillage reduced the need for fungicides in most genotypes in both years. Yields were higher for Bayo Grande and the breeding lines compared to Georgia Green in three of the four experiments across years. When compared across genotype, yields were greatest for the full season fungicide regime, except in 2002 when yields were similar for all treatments. Leaf spot severity was reduced in conservation tillage compared to conventional tillage in most varieties in the absence of fungicides. However, yields tended to be lower in conservation tillage treatments than in conventional tillage. Under conservation tillage, yields of Bayo Grande and two of the breeding lines were negatively impacted in one year and were overall lower in the other year. Several of these new Bolivian-derived genotypes show promise for use in a reduced fungicide and/or conservation tillage IDM system with the potential to lessen fungicide use compared to standard production practices while maintaining low leaf spot levels and high yields.

Economic analysis of experimental organic agricultural systems on a highly eroded soil of the Georgia Piedmont, USA

AbstractInformation about the costs and labor requirements of experimental organic farming systems designed to restore highly degraded soils in the southeastern US are needed. Enterprise budgets were prepared for the production of okra, hot pepper and a corn/winter squash intercrop under 10 different production systems, nine of which were based on organic conservation tillage. A stochastic dominance analysis was conducted to determine the relative risk efficiency of the 10 systems over the course of the experiment in terms of productivity, profitability and carbon sequestration potential. Organic conservation tillage treatments had lower tractor labor and fuel costs than conventional treatments, due to the extensive tillage required in conventional vegetable farming. The subset of organic treatments receiving compost addition without additional mulches also demonstrated increases in soil carbon, an important driver of system productivity. Organic treatments had little pest and pathogen pressure, with the exception of Fusarium wilt in some treatments receiving straw mulch. Weed suppression by straw mulches reduced labor requirements by an average of 23%. Yields in all treatments were lower than conventional yields from other studies in the region, due to the degraded nature of the soil on the study site. However, net returns on high-labor, organic crops were over US$30,000 ha−1 in some treatments. The results of this work indicate that organic, conservation tillage systems can restore soil productivity and command high returns per hectare if labor requirements can be met.

Yield and soil system changes from conservation tillage in dryland farming: A case study from North Eastern Tanzania

Abstract Yield levels in smallholder farming systems in semi-arid sub-Saharan Africa are generally low. Water shortage in the root zone during critical crop development stages is a fundamental constraining factor. While there is ample evidence to show that conservation tillage can promote soil health, it has recently been suggested that the main benefit in semi-arid farming systems may in fact be an in situ water harvesting effect. In this paper we present the result from an on-farm conservation tillage experiment (combining ripping with mulch and manure application) that was carried out in North Eastern Tanzania from 2005 to 2008. Special attention was given to the effects of the tested treatment on the capacity of the soil to retain moisture. The tested conservation treatment only had a clear yield increasing effect during one of the six experimental seasons (maize grain yields increased by 41%, and biomass by 65%), and this was a season that received exceptional amounts of rainfall (549 mm). While the other seasons provided mixed results, there seemed to be an increasing yield gap between the conservation tillage treatment and the control towards the end of the experiment, and cumulatively the yield increased with 17%. Regarding soil system changes, small but significant effects on chemical and microbiological properties, but not on physical properties, were observed. This raises questions about the suggested water harvesting effect and its potential to contribute to stabilized yield levels under semi-arid conditions. We conclude that, at least in a shorter time perspective, the tested type of conservation tillage seems to boost productivity during already good seasons, rather than stabilize harvests during poor rainfall seasons. Highlighting the challenges involved in upgrading these farming systems, we discuss the potential contribution of conservation tillage towards improved water availability in the crop root zone in a longer term perspective.

Extrapolating effects of conservation tillage on yield, soil moisture and dry spell mitigation using simulation modelling

There is big effort to disseminate conservation tillage practices in Tanzania. Despite wide spread field demonstrations there has been some field experiments meant to assess and verify suitability of the tillage options in local areas. Much of the experiments are short lived and thus long term effects of the tillage options are unknown. Experiments to study long term effects of the tillage options are lacking because they are expensive and cannot be easily managed. Crop simulation models have the ability to use long term weather data and the local soil parameters to assess long term effects of the tillage practices. The Agricultural Production Systems Simulator (APSIM) crop simulation model; was used to simulate long term production series of soil moisture and grain yield based on the soil and weather conditions in Mkoji sub-catchment of the great Ruaha river basin in Tanzania. A 24 year simulated maize yield series based on conventional tillage with ox-plough, without surface crop residues (CT) treatment was compared with similar yield series based on conservation tillage (ox-ripping, with surface crop residues (RR)). Results showed that predicted yield averages were significantly higher in conservation tillage than in conventional tillage ( P < 0.001). Long term analysis, using APSIM simulation model, showed that average soil moisture in the conservation tillage was significantly higher ( P < 0.05) (about 0.29 mm/mm) than in conventional tillage (0.22 mm/mm) treatment during the seasons which received rainfall between 468 and 770 mm. Similarly the conservation tillage treatment recorded significantly higher yields (4.4 t/ha) ( P < 0.01) than the conventional tillage (3.6 t/ha) treatment in the same range of seasonal rainfall. On the other hand there was no significant difference in soil moisture for the seasons which received rainfall above 770 mm. In these seasons grain yield in conservation tillage treatment was significantly lower (3.1 kg/ha) than in the conventional tillage treatment (4.8 kg/ha) ( P < 0.05). Results also indicated a probability of 0.5 of getting higher yield in conservation than in conventional tillage practice. The conservation tillage treatment had the ability to even-out the acute and long intra-seasonal dry spells. For example a 36-days agricultural dry spell which occurred between 85th and 130th day after planting in the 1989/1990 season (in the CT treatment) was mitigated to zero days in the RR treatment by maintaining soil moisture above the critical point. Critical soil moisture for maize was measured at 0.55 of maximum soil moisture that can be depleted crop (0.55 D). It is concluded that conservation tillage practice where ripping and surface crop residues is used is much more effective in mitigating dry spells and increase productivity in a seasonal rainfall range of between 460 and 770 mm. It is recommended that farmers in the area adopt that type of conservation tillage because rainfall was in this range (460–770 mm) in 12 out of the past 24 years, indicating possibility of yield losses once in every 2 years.

Tillage practices altered labile soil organic carbon and microbial function without affecting crop yields

A 7-year tillage experiment was conducted on a deep sand in the central wheat belt of Western Australia between 1998 and 2004 to evaluate the impact of tillage intensity [no-tillage (NT), conservation tillage (CT), and rotary tillage (RT)] on soil organic matter, microbial biomass and function, and crop yields in a wheat–lupin rotation. A fourth treatment (subterranean clover pasture, Pasture) with least soil disturbance was included as a comparison. By March 2004, total soil carbon (C) in NT and CT increased by 4.4 and 2.6 t/ha, respectively, to an average of 17.6 t/ha in the top 0.1 m of the soil profile. There was a loss of total soil C in RT (–0.5 t/ha), which was significant compared with the other 2 tillage treatments. Total soil C and nitrogen (N) contents in the pasture treatment were similar to those in NT and CT at the end of the experiment. Labile fractions of soil C responded more rapidly to tillage practice, with significant reductions by 2001 in light fraction C and dissolved organic C in the RT treatment compared with the other 3 treatments. The effect of RT on biology and function was seen early in the experiment and, compared with Pasture, NT, and CT, intense tillage in RT significantly reduced microbial biomass and cellulase activity in the surface 0.05 m by the third year of the experiment. However, at a depth of 0.05–0.10 m there were no significant differences between treatments. Grain yields in NT, CT, and RT were unaffected by tillage except in 2003, when lupin yield under RT (1.6 t/ha) was significantly less than under NT (2.0 t/ha) and CT (1.9 t/ha). Minimal differences between NT and CT are a reflection of the minimum disturbance in the CT treatment, although there were significant differences between CT and NT in microbial indices such as microbial quotient and metabolic quotient, suggesting a future divergence of these treatments.

Influence of 10 years of conservation tillage on some biological properties of a fine sandy loam in the potato phase of two crop rotations in Atlantic Canada

Conservation practices in potato (Solanum tuberosum L.) cropping systems can reduce excess tillage, provide crop residue cover, and maintain crop productivity; however, little is known about their long-term influence on soil biota and biological properties. Conservation tillage was evaluated in two potato rotations: a 2-yr barley-potato rotation and 3-yr clover-based (barley-red clover-potato) rotation initiated in 1994 on a fine sandy loam (Orthic Podzol) in Prince Edward Island, eastern Canada. Soil samples were obtained in 2003 from the 0- to 10-cm soil depth of the potato phase of both rotations to evaluate the influence of conservation, compared with conventional tillage, on changes in soil fertility, soil structural properties, soil C and N fractions, soil-borne pathogens, nematode communities, and micro-arthropod (Collembola and Acari) communities. The 3-yr conservation tillage practice improved soil structural stability, increased soil extractable P and K, increased soil organic C and total N and their particulate fractions, compared with the other treatments. Comparisons with earlier studies indicated that soil organic C had reached an equilibrium level at the 0- to 10-cm soil depth. Reduction of potato disease caused by Rhizoctonia solani was evident in the 3-yr rotation, compared with the 2-yr rotation, but was not influenced by tillage practice. Plant parasitic nematodes were not greatly influenced by rotation and tillage treatments; however, densities of the beneficial bacterial-feeding nematodes were increased under the 3-yr conservation tillage treatment. The abundance of micro-arthropods was increased by conservation tillage, while their diversity was mainly influenced by the rotation cycle rather than tillage practice. Overall, the 3-yr conservation tillage treatment provided a more beneficial soil biological condition than the other treatments, especially when compared with the 2-yr conventional tillage practice. Key words: Conservation systems, potato rotation, fine sandy loam, soil fertility, soil organic C and N fractions, soil structure, soil-borne pathogens, nematode, Collembola; Acari

The influence of tillage systems on soil organic matter and soil hydrophobicity

Management practices including various tillage systems influence quantity and composition of soil organic matter (SOM). Parameters for evaluating both the SOM quantity (organic C [C ox], total N [N t]) and quality (microbial biomass C, hydrophobic and hydrophilic organic components) were determined in soil samples, taken from two soil depths (0–0.1 m and 0.1–0.3 m) in a field experiment in the period 2001–2007, with different tillage systems. The experiment, founded in 1995 in Prague-Ruzyně, includes conventional soil tillage (CT) plus some selected methods of conservation tillage: (a) no tillage (NT), (b) no tillage + mulch (NTM), and (c) minimum tillage with pre-crop residues incorporated (MTS). C ox and microbial biomass C contents increased significantly with conservation tillage as compared to CT in 0–0.1 m layer, non-significant increase was found in 0.1–0.3 m layer. N t increased non-significantly in both layers. Along with the depth of sampling, the content of the characterized parameters decreased in all variants; but the decrease in the conventionally tilled variant was, for the most part, lower than in the conservation tillage. The functional hydrophobic and hydrophilic groups of soil organic matter were identified by Fourier transform infrared (FTIR) spectroscopy, and the hydrophobic/hydrophilic group intensities ratio was calculated as the parameter of soil hydrophobicity. A higher soil hydrophobicity existed in all three conservation tillage treatments compared to CT due to the significantly higher content of hydrophobic organic components. C ox correlated significantly with microbial biomass C, N t, hydrophobic components, and soil hydrophobicity ( R = 0.552–0.654; P < 0.05). Hydrophilic components did not correlate with other soil characteristics, with the exception of hydrophobic components. These data show that shifting from CT to the conservation tillage systems increased the content of SOM in top soil layer in relatively short time, improved the SOM quality and increased soil hydrophobicity in the condition of experiment.

Influence of conservation tillage practices on soil properties and crop yields for maize and wheat cultivation in Beijing, China

Conservation tillage is becoming increasingly attractive to farmers because it involves lower production costs than does conventional tillage. The long-term effects of sub-soiling tillage (ST), no tillage (NT), and conventional tillage (CT) on soil properties and crop yields were investigated over an 8-year period (2000–07). The study was conducted in a 2-crop-a-year region (Daxing) and a 1-crop-a-year region (Changping) of the Beijing area in China. At 0–0.30 m soil depth, water stability of macro-aggregates (&gt;0.25 mm) was much greater for ST (22.1%) and NT (12.0%) than for CT in Daxing, and the improvements in Changping were 18.9% and 9.5%, respectively. ST and NT significantly (P &lt; 0.05) improved aeration porosity by 14.5% and 10.6%, respectively, at Daxing and by 17.0% and 8.6% at Changping compared with CT treatment. Soil bulk density after 8 years was 0.8–1.5% lower in ST and NT treatments than in CT at both sites. Soil organic matter and available N and P followed the same order ST ≈ NT &gt; CT at both sites. Consequently, crop yields in ST and NT plots were higher than in CT plots due to improved soil physical and chemical properties. Within the conservation tillage treatments, despite similar economic benefit, the effects on crop yields for ST were better than for NT. Mean (2000–07) crop yields for ST were 0.2% and 1.5% higher than for NT at Daxing and Changping, respectively. We therefore conclude that ST is the most suitable conservation tillage practice for annual 2-crop-a-year and 1-crop-a-year regions in the Beijing area.

EFFECT OF SOIL MANAGEMENT ON THEIR THERMAL PROPERTIES

In order to determine the effect of soil management on its thermal properties, undisturbed soil samples were taken from two tillage treatments (conventional and conservation treatment) at two depths (0-30cm and 30-60cm) of a Stagnic Luvisol (silt loam) before and after directly wheeling. The experimental field, located in Harste/Goettingen, Germany, was cultivated with sugar beet (Beta vulgaris). To calculate thermal properties of the soil, the volumetric water content (TDR needles) and temperature (pT 100 thermistors) during the simulation of the daily fluctuation of temperature were registered in laboratory and then the thermal conductivity, volumetric heat capacity and heat diffusivity were calculated following the damping depth method and the statistical-physical model. The results showed that different tillage systems as well as compaction influenced soil thermal properties. Conservational tillage treatment with more stable and better developed soil structure at a depth of 0-30cm (which represents ploughing depth and decides differences between soil management) presented higher water content as the main factor deciding soil thermal properties. According to this, values of thermal conductivity and volumetric heat capacity under this treatment were greater than under conventional. Thermal diffusivity, however, was lower. From the latter we can conclude that under conservation tillage treatment the soil can store more heat, but at the same time and as a result of the lower thermal diffusivity, the atmospheric variations do not affect the soil thermal regime strongly.

Functional relationships between soil water infiltration and wheeling and rainfall energy

Surface seal formation and subsoil compaction are two important factors of soil structural degradation, both of which reduce infiltration and increase surface runoff. Surface sealing has traditionally been related to rainfall energy; however, there has been very limited work on characterizing subsoil degradation resulting from wheeling energy imposed by agricultural machinery traffic. The objective of this study was to test the hypothesis that wheeling energy, either by itself or in combination with rainfall energy, would be a useful predictor of subsequent soil structural degradation. Field experiments were conducted on a heavy clay soil site in South-east Queensland, Australia which had controlled traffic and conservation tillage treatments for the previous 5 years. Soil was compacted with different axle load and wheel slips, and wheeling energy was calculated from wheel slip and rolling resistance. Simulated rain was applied at different intensities with a portable rainfall simulator. Runoff was measured with a tipping bucket flow meter, and infiltration parameters and the corresponding curve number was determined. The results showed that when soil was protected by residue cover, infiltration and runoff was governed by subsoil compaction. Under this condition, steady state infiltration rate decreased and curve number increased with increasing wheeling energy, but the constant values of steady infiltration rate (14.5 mm h −1) and curve number (93) resulted after wheeling energy exceeded 5 kJ m −2. Under non-wheeled conditions, steady state infiltration rate decreased and curve number increased linearly with increasing cumulative rainfall energy. The limited data set suggests that the degradation of soil hydraulic properties appears to be related to the sum of wheeling and rainfall energy. The data confirms that rainfall energy causes surface soil degradation, while wheeling energy caused subsoil soil degradation. Wheeling energy is relatively easy to measure or estimate, and appears to also be a useful predictor of subsoil soil degradation.

Effect of alternative tillage and residue cover on yield and water use efficiency in annual double cropping system in North China Plain

In the annual double cropping areas of North China Plain, low crop yield and water availability are the main limiting factors to crop production. Conservation tillage has been proposed to improve water conservation and sustain soil productivity. The objectives of the study were to compare conservation tillage (CT) with conventional tillage (CV) under the current double cropping system of corn-winter wheat in the Hebei, North China Plain. The field study consisted of eight conservation tillage treatments and two conventional tillage treatments, with different surface ground cover (0%, 50% and 100%). The tillage treatments consisted of no-till, subsoiling, rototilling and plowing. The CT treatments maintained soil temperatures that were approximately 0.4 °C greater during cold condition and about 0.5 °C lower during warm condition at 5 and 10 cm soil depths than the CV treatments, respectively. The greatest differences were achieved by the double no-till system with 100% residue cover treatment in terms of soil temperature and crop growth. Winter wheat yield and water use efficiency (WUE) were improved by 6.7% and 30.1% with CT compared to the CV treatments, and for corn, 8.9% and 6.8%, respectively. We conclude that conservation tillage for the annual double cropping system is feasible, and the double no-till with 100% residue cover is the most effective way of improving crop yields and WUE on the North China Plain.

Tillage and Nitrogen Application Methodology Impacts on Corn Grain Yield

ABSTRACT Increased fuels costs have prompted many producers to consider conservation tillage techniques and single pass applications of nitrogen (N) fertilizer and herbicide to reduce fuel expenses. The objective of this study was to determine the impacts of tillage and nitrogen application methodology on corn grain yield. The experiment was conducted from 2002–2005 at the Northwest Research Station of the Ohio Agricultural Research and Development Center (OARDC) near Hoytville, OH. Six different tillage regimes were established as main plots: no-till, fall disc-field cultivator, Aerway tool tillage, early planted strip-till, late planted strip-till, and zone deep-till. Subplots consisted of either a single-pass application of broadcast, surface applied urea-ammonoium nitrate (UAN) representing a weed ‘n’ feed application, a split application of nitrogen between planter applied and sidedress N (subsurface injected N), or an unfertilized control. The rate of N for the different application methodologies was 168 kg ha−1. Dry conditions during the 2002 growing season resulted in very poor corn yield and thus little response to tillage or N application. In 2003, the split treatment maximized corn yield likely due to minimized ammonia volatilization independent of tillage regime. Surface broadcast applications of UAN resulted in lower grain yields in conservation tillage treatments compared to split nitrogen applications in 2004. No statistical differences were noted between the two application methods in the conventional tillage treatments. In 2005, no yield differences could be attributed to N application methodology across tillage treatments. From this study it was concluded that surface broadcast application of UAN can result in yield loss, especially in conservation tillage systems.

Soil Conservation Tillage Effects on Yield and Water Use Efficiency on Irrigated Crops in Central Italy

AbstractDespite possible agronomic and environmental benefits, the diffusion of soil conservation tillage systems in Italy is currently rather low. The aim of this study was to compare the performance of different soil tillage techniques, in an effort to identify suitable soil management options for irrigated crops in Central Italy. An experiment was carried out on maize and soybean from April to October in two consecutive years (1993 and 1994) in Maccarese (a coastal location near Rome). The systems compared were: conventional mouldboard ploughing (CT), minimum tillage, ridge tillage and no‐tillage (NT). In 1993, actual crop evapotranspiration was measured throughout the growing season on NT and CT soybean, using a micrometeorological technique.No significant differences due to soil tillage were found for grain yield and yield irrigation water use efficiency (IWUEy), except for soybean in 1994, in which yields and IWUEy were 59 % higher on conservation tillage treatments compared with CT. In 1994 soybean yield water use efficiency was 10.1 and 9.5 kg ha−1 mm−1 for NT and CT respectively. The results suggest that the adoption of soil conservation tillage is feasible, for the specific cropping system, with equivalent or better performances as conventional tillage.

Evaluating a crop residue cover index for determining tillage regime in a cotton-corn-peanut rotation

Conservation tillage is a well known best management practice that improves soil quality, reduces runoff and erosion, and increases infiltration. However, a rapid assessment strategy for quantifying the rate and spatial distribution of conservation tillage practices is lacking. This study was designed to evaluate the sensitivity of a remotely derived crop residue cover index for depicting conventional tillage (CT), strip tillage (ST), and no-tillage (NT) systems in a cotton-corn-peanut rotation in the southeastern Coastal Plain. Treatments consisted of CT (rip and bed operation), NT, NT with subsoiling, and ST. Remotely sensed data were acquired three times prior to canopy closure, using a handheld multispectral radiometer (485 to 1,650 nm) and thermal imager (7,000 to 14,000 nm). Using a combination of visible and near-infrared spectra, a crop residue cover index was calculated and evaluated. Results showed that crop residue cover is greatest in years planted with peanut or cotton—likely due to the later winter cover crop termination date compared to years when corn is planted. The crop residue cover index outperformed the thermal infrared, accurately separating conventional from conservation tillage treatments in four out of six data acquisitions in 2004 and 2006. Differentiation among conservation tillage treatments was inconsistent. Regression analyses showed that a strong linear relationship existed between the crop residue cover index and measured crop residue cover (<i>r</i>² = 0.51 to 0.86, alpha = 0.10). These data suggest that remotely sensed data may be used as a rapid, field-scale indicator of conservation tillage adoption. Rapid assessment methodologies are necessary to quantify the impact of conservation practice adoption on water quality/quantity, assess adoption rates, and improve the placement of conservation tillage practices at local, watershed and regional scales.

Evaluating a crop residue cover index for determining tillage regime in a cotton-corn-peanut rotation

Conservation tillage is a well known best management practice that improves soil quality, reduces runoff and erosion, and increases infiltration. However, a rapid assessment strategy for quantifying the rate and spatial distribution of conservation tillage practices is lacking. This study was designed to evaluate the sensitivity of a remotely derived crop residue cover index for depicting conventional tillage (CT), strip tillage (ST), and no-tillage (NT) systems in a cotton-corn-peanut rotation in the southeastern Coastal Plain. Treatments consisted of CT (rip and bed operation), NT, NT with subsoiling, and ST. Remotely sensed data were acquired three times prior to canopy closure, using a handheld multispectral radiometer (485 to 1,650 nm) and thermal imager (7,000 to 14,000 nm). Using a combination of visible and near-infrared spectra, a crop residue cover index was calculated and evaluated. Results showed that crop residue cover is greatest in years planted with peanut or cotton-likely due to the later winter cover crop termination date compared to years when corn is planted. The crop residue cover index outperformed the thermal infrared, accurately separating conventional from conservation tillage treatments in four out of six data acquisitions in 2004 and 2006. Differentiation among conservation tillage treatments was inconsistent. Regression analyses showed that a strong linear relationship existed between the crop residue cover index and measured crop residue cover (r2 = 0.51 to 0.86, alpha = 0.10). These data suggest that remotely sensed data may be used as a rapid, field-scale indicator of conservation tillage adoption. Rapid assessment methodologies are necessary to quantify the impact of conservation practice adoption on water quality/quantity, assess adoption rates, and improve the placement of conservation tillage practices at local, watershed and regional scales.

Tillage and Cover Cropping Effects on Aggregate‐Protected Carbon in Cotton and Tomato

Conservation tillage (CT) and cover cropping (CC) are agricultural practices that may provide solutions to address water and air quality issues arising from intensive agricultural practices. This study investigated how CT and CC affect soil organic matter dynamics in a cotton(Gossypium hirsutum L.)–tomato (Lycopersicon esculentum Mill.) rotation in California's San Joaquin Valley. There were four treatments: conservation tillage, no cover crop (CTNO); conservation tillage with cover crop (CTCC); standard tillage, no cover crop (STNO); and standard tillage with cover crop (STCC). After 5 yr, the top 30 cm of soil in CTCC had an increase of 4500 kg C ha−1, compared with an increase of 3800 kg C ha−1 in STCC from initial soil C content in 1999. To enhance our understanding of C dynamics in CT systems, we pulse‐labeled cotton with 13CO2 in the field and followed the decomposition of both the roots and the shoots through three physical fractions: light fraction (LF), which tends to turnover quickly, and two relatively stable C pools—intraaggregate LF (iLF) and mineral‐associated carbon (mC). Soil under CT treatments retained more of the cotton‐residue‐derived C in LF and iLF than ST 3 mo after placement in the field. These differences disappeared after 1 yr, however, with no discernable differences between CT and ST regardless of CC. In California's Mediterranean climate, CT alone does not accumulate or stabilize more C than ST in tomato–cotton rotations, and the addition of cover crop biomass is more important than tillage reduction for total soil C accumulation.

INCREASE OF SOIL STRENGTH OVER TIME IN A US SOUTHEASTERN COASTAL PLAIN LOAMY SAND

With rising energy costs, fuel-consumptive soil management practices, such as deep tillage, need to be reassessed to determine whether they need to be performed every year or not. Between 1978 and 1996, conservation (nondisked) and conventional (disked) tillage treatments had been annually deep-tilled with noninversion subsoiling to break up a subsurface layer that had high soil strength, associated with the E horizon of a coastal loam sand. After 1996, treatments were split with half being deep-tilled until 2001, after which no treatments were deep-tilled, although surface tillage continued. By 1999, soybean (Glycine max L. Merr.) treatments in which deep tillage ceased in 1996 were significantly higher in cone index (as measured by a penetrometer) than were treatments that had been deep-tilled, suggesting that the effects of deep tillage lasted three years. By 2004, conventional treatments in which tillage ceased in 2001 had reconsolidated to the point that they were not different from conventional treatments where tillage had ceased in 1996. However, conservation tillage treatments were still significantly different, suggesting that conservation tillage can help buffer the effects of reconsolidation. Two competing trends could be observed. On the one hand, although reconsolidation might not be complete, soils with incomplete reconsolidation could be hard enough to reduce production. On the other hand, soils in which tillage ceased still showed the effects of deep tillage even after they reconsolidated to the point that they were statistically different from deep-tilled treatments.

A conservation-tillage, cover-cropping strategy and economic analysis for creamer potato production

A two-year experiment was conducted at the Beltsville Agricultural Research Center (BARC), MD, and Virginia Polytechnic Institute and State University Kentland Agricultural Research Farm (KARF), VA, to evaluate potato (Solanum tuberosum L.) production of 32- to 57-mm-size-range tubers (referred to hereafter as creamers) in a conservation-tillage, cover-cropping strategy. The experiments used a split-plot design in which the main-plots were cover crop treatments and the sub-plots were different potato selections. Main plot treatments included rye (Secale cereale L.), crimson clover (Trifolium incarnatum L.), Austrian winter pea (Pisum sativum L.), rape (Brassica napus L.), oat (Avena sativa L.), rye/crimson clover mixture, rape/crimson clover mixture, bare soil/raised beds, and bare soil/flat beds (control). Potato selections tested were B1145-2, B1491-5, and B1492-12 in 2000 and B1145-2, B1102-3, and B0811-4 in 2001. Yields in the conservation-tillage treatments were equal to or better than those in the bare soil/flat bed control with few exceptions. Large-sized tubers (<57 mm) in almost all cases remained below 6% of total marketable yield even when the tubers were harvested late. Delayed harvest did not reduce creamer-sized yields nor did it increase yield of large-sized tubers. Economic analysis shows that net returns from some conservation-tillage treatments are equal to or higher than the conventional-tillage strategy and confirms the viability of the conservation-tillage, cover-cropping strategy. Furthermore, the conservation-tillage strategy in many cases allows timely planting using machinery in the wet soils of Maryland and Virginia during the narrow window of spring potato planting time, whereas the conventional tillage strategy does not offer this advantage.