Search

Potential carbon mineralization (Cmin) is a commonly used indicator of soil health, with greater Cmin values interpreted as healthier soil. While Cmin values are typically greater in agricultural soils managed with minimal physical disturbance, the mechanisms driving the increases remain poorly understood. This study assessed bacterial and archaeal community structure and potential microbial drivers of Cmin in soils maintained under various degrees of physical disturbance. Potential carbon mineralization, 16S rRNA sequences, and soil characterization data were collected as part of the North American Project to Evaluate Soil Health Measurements (NAPESHM). Results showed that type of cropping system, intensity of physical disturbance, and soil pH influenced microbial sensitivity to physical disturbance. Furthermore, 28% of amplicon sequence variants (ASVs), which were important in modeling Cmin, were enriched under soils managed with minimal physical disturbance. Sequences identified as enriched under minimal disturbance and important for modeling Cmin, were linked to organisms which could produce extracellular polymeric substances and contained metabolic strategies suited for tolerating environmental stressors. Understanding how physical disturbance shapes microbial communities across climates and inherent soil properties and drives changes in Cmin provides the context necessary to evaluate management impacts on standardized measures of soil microbial activity. Foundation for Food and Agricultural Research [523926]; Samuel Roberts Noble Foundation; General Mills Published version Foundation for Food and Agricultural Research (grant ID 523926), General Mills, and The Samuel Roberts Noble Foundation.

Recently biochar has attracted attention as a soil amendment and soil organic carbon source which can be used to modify soil quality. Although the effects of biochar on individual soil quality parameters are well established, the impacts on soil quality indexes are rather limited or less known. Soil samples were collected from a two year controlled experiment treated with various levels of biochars (0, 4 and 8 Mg ha−1) obtained from three locally available materials (cotton straws, pistachio shells and corn cobs) and two different irrigation regimes 100% (FC100) and 65% of field capacity (FC65). Soil samples were collected and analyzed for important soil quality indicators; soil organic matter, aggregate stability, bulk density, porosity, available water content, hydraulic conductivity and total nitrogen. A Soil Quality Index (SQI) of multiple measured soil parameters for each parcel was obtained using both linear and non-linear scoring functions. Biochar application improved all soil quality parameters investigated and soil quality indexes and these improvements were more prominent in FC65 parcels than those in FC100 parcels. Soil quality indexes were significantly increased with a synergistic impact of biochar applications with a range from 3.9% to 138.5% depending on treatments and scoring function used. The results from these field studies showed that carbon rich biochars obtained from locally available plant residues can be applied to improve soil qualities on the degraded, low organic matter soils of the Harran Plain.

Soil health, or soil quality, is defined as the continued capacity of soil to function as a vital living ecosystem that sustains plants, animals, and humans. Traditional views of soil quality often considered soils from the perspective of crop productivity and soil chemical properties, which generally led to an undervaluation of soil biological and physical processes. Soil health is a complex concept that requires a broader understanding of soil properties. It can be implemented through the comprehensive assessment of soil health (CASH) approach, which measures 15 physical, biological, and chemical soil indicators that can be linked to management recommendations. This chapter discusses all 15 tests, including the soil sampling and sample preparation methodologies. The methodology of the eight biological and physical tests is also covered in detail. These measures are interpreted through scoring functions that provide an overall soil health score. A comparison of indicator values between India, Colombia, and three US regions illustrates the need for scoring functions to be regionally adapted to production environments.

The performance of no-till (NT) in temperate regions may be enhanced through the integration of additional conservation practices such as cover cropping and crop rotations. This study assessed the long-term impacts of continuous (20+ years) NT in comparison to plow-till (PT) management on soil properties and corn (Zea mays L.) yields in New York. The effects of tillage were assessed in combination with different cropping systems (24 years corn monoculture vs. 12 years corn monoculture; and with or without interseeded cover crops) on three soil textures: clay loam, loamy sand and silt loam. We measured four soil biological indicators - organic matter (OM), active carbon (ActC), respiration (Resp) and protein (Prot); four soil physical indicators - available water capacity (AWC), water stable aggregation (WSA), penetration resistance (PR) and water infiltration rate (InfRate); soil chemical indicators (plant available nutrients, pH and total N), and corn yield. Soil managed under long-term NT showed the most favorable soil biological, physical and chemical conditions for plant development, with higher levels of OM, Prot, Resp, WAS, total N, P and Zn, and InfRate. Benefits of introducing a grass-legume cover crop mixture into the cropping system were evident after 4 years for OM, Prot, Resp, AWC, Fe and Zn. Cover crop effects were greater under NT than PT, and additive to the NT benefits. On the clay loam soil, the effects of a 6-year interruption of continuous corn production with a perennial grass crop were still discernable with several soil health indicators 12 years after resuming corn production under NT. The better soil conditions under NT resulted in higher corn yields in both the loamy sand and silt loam soils, but not the clay loam. Our study shows that long-term NT can be viable in temperate regions, promoting significant improvement in soil health and crop yield and that these benefits are enhanced when NT is combined with crop rotation (perennial grass) and cover crops.

Intensive agriculture is an emerging theme of green roof technology. Production of affordable, nutritious vegetables for local consumption and stormwater management are among the ecosystem services emphasized in studies of rooftop farming. However, intensive vegetable production requires irrigation, which can reduce stormwater retention, and there is little empirical data from full-scale operational rooftop farms. In this paper, we report the hydrologic performance of the Brooklyn Grange Navy Yard Farm, a 0.61-ha rooftop farm atop an 11-story building in New York City USA. We monitored soil water content, precipitation, irrigation, drainage, and crop yields to provide water balance and water use efficiency. We found cumulative discharge exceeded precipitation by 11% during the entire study period, hence the farm was a net source of water in the urban hydrologic cycle. Depending on crop types, water use efficiency at the Grange was lower than in-ground agriculture in dry regions with high irrigation demands. For the Brooklyn Grange to integrate stormwater management and water-efficient crop production, it will be important to increase soil water storage, to reduce irrigation demands and drainage loss of water while maintaining average soil moisture levels in the range of readily available water between 10 and 100 kPa of soil water tension.

Both surface and subsoil layers can be a significant source of soil moisture and nutrients for crop growth, but the changes in subsoil properties due to management are rarely assessed. This study was conducted to determine tillage and residue management effects on soil nutrient availability, as well as soil biological and physical conditions throughout soil layers ranging from 0 to 60 cm. We utilized an experiment with 40-year long continuous maize (Zea mays L.) cropping under crossed plow-till (PT) vs. no-till (NT) and residue removed (Harv) vs. residue returned (Ret) treatments on a silt loam soil in Chazy, NY. We assessed soil properties that are indicative of soil processes important for crop growth. Soil physical indicators (texture, bulk density (BD), water stable aggregation (WSA), available water capacity (AWC), and air-filled porosity (AFP)), soil biological indicators (soil organic matter (SOM), permanganate oxidizable carbon, mineralizable carbon, and soil protein), and soil chemical indicators (pH and plant available nutrients) were measured at five depth increments (0–6, 6–18, 18–30, 30–45, and 45- to 60-cm depth). A novel statistical approach of marginal R2 (R2m) was used to show percent variance of each measured soil indicator explained by tillage and residue management as well as the depth of soil sample. R2m was higher for soil biological indicators (0.66

We report brown root rot (BRR) of alfalfa, caused by the fungal pathogen Phoma sclerotioides, for the first time in the eastern United States. Alfalfa production fields in New York, Vermont, and New Hampshire were sampled in spring 2005, and soil characteristics were related to variability in BRR incidence and severity in two New York fields sampled extensively. BRR was detected in 8 of 10 fields sampled in New York, 6 of 7 fields sampled in Vermont, and 5 of 6 fields sampled in New Hampshire. Lesions on both roots and crowns were common in all three states, and most BRR lesions extended into the cortical tissues. Diagnostic polymerase chain reaction (PCR) of P. sclerotioides isolates produced a single amplicon of the expected size. In vivo conidia and pycnidia morphology of northeastern isolates was consistent with published descriptions of P. sclerotioides, and P. sclerotioides was reisolated from symptomatic lesions after pathogenicity testing. In two New York fields sampled extensively, BRR severity varied with soil strength, soil texture, soil saturation, and alfalfa stand density. The spatial pattern of BRR within fields suggests the pathogen was not recently introduced. The results suggest BRR is widespread in alfalfa production fields in New York, Vermont, and New Hampshire.

Large temporal and spatial variability in soil nitrogen (N) availability leads many farmers across the United States to over-apply N fertilizers in maize (Zea Mays L.) production environments, often resulting in large environmental N losses. Static Stanford-type N recommendation tools are typically promoted in the United States, but new dynamic model-based decision tools allow for highly adaptive N recommendations that account for specific production environments and conditions. This study compares the Corn N Calculator (CNC), a static N recommendation tool for New York, to Adapt-N, a dynamic simulation tool that combines soil, crop, and management information with real-time weather data to estimate optimum N application rates for maize. The efficiency of the two tools in predicting the Economically Optimum N Rate (EONR) is compared using field data from 14 multiple N-rate trials conducted in New York during the years 2011 through 2015. The CNC tool was used with both realistic grower-estimated potential yields and those extracted from the CNC default database, which were found to be unrealistically low when compared with field data. By accounting for weather and site-specific conditions, the Adapt-N tool was found to increase the farmer profits and significantly improve the prediction of the EONR (RMSE = 34 kg ha⁻¹). Furthermore, using a dynamic instead of a static approach led to reduced N application rates, which in turn resulted in substantially lower simulated environmental N losses. This study shows that better N management through a dynamic decision tool such as Adapt-N can help reduce environmental impacts while sustaining farm economic viability.

Changes in the profile distribution of soil C stocks for conventional versus no-tillage can affect N2O losses. Uncertainty remains whether deep N placement into a wetter layer in humid areas would affect N2O losses. This study evaluated the effects of soil carbon profile distribution (inverted, normal), depth of nitrogen placement (5 cm, 15 cm), temperature (10, 20 and 30 °C) and soil texture (clay loam, loamy sand) on N2O emissions from soil cores in a 216-h incubation after simulated rainfall. N2O losses were larger from the clay loam than from the loamy sand, and cumulative N2O emissions from the inverted profile, with greater C levels at depth, were more than those from the profile with more C near the upper surface. Cumulative N2O losses from the inverted clay loam profile with deep N placement (1.16 mg N per kg dry soil; 0.71% of applied N) on average were almost double those in the loamy sand (0.62 mg N per kg dry soil; 0.42%). The smallest N2O losses were measured from the profiles with more C close to the upper surface with a shallow placement of N for the clay loam (0.19 mg N per kg dry soil; 0.12%) and loamy sand (0.33 mg N per kg dry soil; 0.23%). An exponential relationship between N2O fluxes and temperature was measured. We conclude that large N2O losses may occur under the combination of greater soil C content at deeper layers (ploughed soils) and moist profiles after N application (humid regions). Deep N placement appears to aggravate rather than ameliorate these concerns.

We investigated soil quality in a ‘Liberty’ apple (Malus × domestica Borkh.) orchard on ‘M.9’ rootstocks, during and after transition from conventional to integrated (IFP) and organic (OFP) fruit production systems. Chemical composition, physical properties, and biological properties were measured at 0–6 and 6–12 cm soil depths over four years. Weed coverage and biomass were also measured. Terminal-restriction fragment length polymorphism analyses determined soil bacterial and fungal community compositions. Mulch with infrequent herbicide application provided effective weed control in IFP, and increased soil organic matter, pH, nutrient availability, microbial biomass C, and microbial respiration. Mechanical cultivation and chicken manure compost were used for OFP, which increased soil porosity, decreased aggregate stability, and increased potentially mineralizable and total inorganic N. Under OFP, cultivation suppressed weeds for 2–4 week intervals, but overall weed coverage was greater than under IFP. For most measurements, minimal treatment differences were found at 6–12 cm soil depth. Sampling time influenced bacterial communities more than the treatments but by the final sampling dates, fungal communities in the 0–6 cm depth segregated by treatment. Soil quality did not improve as much in OFP as in the IFP system soil.

Loss of agroecosystem soil functions due to soil quality (SQ) degradation impacts Africa's agricultural viability and food security. Primary forest and farm fields deforested between 1930 and 2000 were sampled along a chronosequence on two parent materials in western Kenya. Two traditional long-term management systems were sampled: continuous low-input maize (Zea mays; Co), and kitchen garden (Ki) polyculture with organic inputs. Physical, biological, and chemical SQ indicators were measured. Degradation in Co followed exponential decay trends for most indicators (organic matter, active C, water-stable aggregates, available water capacity, electrical conductivity, CEC, pH, Ca, Mg and Zn), as well as for yield. Organic matter quality declined linearly, suggesting degradation will continue. For both parent materials and most indicators degradation of 25–93% below initial values resulted, but with ≤40% further drop below initial values and for more indicators under Co than Ki. P, Zn and possibly K accumulated over time under Ki. The extent of degradation was influenced by parent material. In conclusion, a basic accessible set of SQ indicators was successfully used to describe soil degradation dynamics under cultivation. Results suggest that regular organic inputs can significantly reduce degradation, especially of nutrient retention and soil structure, after forest conversion.

Understanding the response of soil quality indicators to changes in management practices is essential for sustainable land management. Soil quality indicators were measured for 2 years under established experiments with varying management histories and durations at four locations in New York State. The Willsboro (clay loam) and Aurora (silt loam) experiments were established in 1992, comparing no-till (NT) to plow-till (PT) management under corn (Zea maysL.)–soybean (Glycine maxL.) rotation. The Chazy (silt loam) trial was established in 1973 as a factorial experiment comparing NT versus PT and the crop harvesting method (corn silage versus corn grain). The Geneva (silt loam) experiment was established in 2003 with vegetable rotations with and without intervening soil building crops, each under three tillage methods (NT, PT and zone-till (ZT)) and three cover cropping systems (none, rye and vetch). Physical indicators measured were wet aggregate stability (WAS), available water capacity (AWC) and surface hardness (SH) and subsurface hardness (SSH). Soil biological indicators included organic matter (OM), active carbon (AC), potentially mineralizable nitrogen (PMN) and root disease potential (RDP). Chemical indicators included pH, P, K, Mg, Fe, Mn and Zn. Results from the Willsboro and Aurora sites showed significant tillage effects for several indicators including WAS, AWC, OM, AC, pH, P, K, Mg, Fe and Mn. Generally, the NT treatment had better indicator values than the PT treatments. At the Chazy site, WAS, AWC, OM, AC, pH, K and Mg showed significant differences for tillage and/or harvest method, also with NT showing better indicator values compared to PT and corn grain better than corn silage. Aggregate stability was on average 2.5 times higher in NT compared to PT treatments at Willsboro, Aurora and Chazy sites. OM was also 1.2, 1.1 and 1.5 times higher in NT compared to PT treatments at Willsboro, Aurora and Chazy sites, respectively. At the Geneva site WAS, SH, AC, PMN, pH, P, K and Zn showed significant tillage effects. The cover crop effect was only significant for SH and PMN measurements. Indicators that gave consistent performance across locations included WAS, OM and AC, while PMN and RDP were site and management dependent. The composite soil health index (CSHI) significantly differentiated between contrasting management practices. The CSHI for the Willsboro site was 71% for NT and 59% for PT, while at the Aurora site it was 61% for NT and 48% for PT after 15 years of tillage treatments.

Soil nitrate (NO3) can be especially susceptible to leaching and denitrification in late spring under maize (Zea mays L.) production. This study examined the effects of tillage (untilled; tilled), fertilizer application (full season rate or starter-only at planting), rotation (maize after orchardgrass (Dactylis glomerata L.); continuous maize), and soil type (clay loam; loamy fine sand) on short-term nitrous oxide (N2O) emissions after a 50-mm late-spring simulated precipitation event. N2O emissions were measured daily for a week following the event. Soil NO3, temperature, physical properties and total N were also measured. N2O emissions peaked on the second day after a simulated rainfall event for all treatments. N2O losses were significantly higher on the clay loam compared to the loamy sand. Full season fertilizer application at planting on untilled soil resulted in 4.7 and 2.3 kg N ha−1 greater cumulative N2O losses than starter-only fertilizer application on maize-after-grass and continuous maize, respectively. Under tilled conditions, cumulative N2O losses over a week averaged 0.88 kg N ha−1 greater for the full fertilizer application compared to the starter-only application. Higher N2O losses from untilled soil were related to lower soil porosity and higher bulk density, and higher emissions under maize-after-grass were correlated with higher soil C levels. In conclusion, untilled soil and sod-based crop rotations increase late-spring N2O losses under maize production, especially with early fertilization.

Approaches to measuring air and water quality are well established, but soil quality assessment protocols to be used in landscape monitoring efforts are largely non-existent. The concept of soil quality represents the integration of the physical, biological, and chemical aspects of soils. Limited attention has been given to the holistic assessment of soil quality in landscape and urban planning, as it is typically addressed only through chemical analyses. We describe the process used for the selection of soil quality indicators that are being offered as part of the new Cornell Soil Health Test. Over 1500 samples were collected from agricultural landscapes, including controlled experiments, and analyzed for 39 potential soil quality indicators. Four physical and four biological soil indicators were selected based on sensitivity to management, relevance to functional soil processes, ease and cost of sampling, and cost of analysis. Seven chemical indicators were selected as they constitute the standard soil fertility test. For potentially contaminated sites, additional chemical indicators were considered through a total elemental analysis. Test reports were developed to allow for overall soil quality assessment and the identification of specific soil constraints that may be remedied through management practices. The use of the new soil quality test is exemplified for three landscape scenarios in New York State: a vegetable farm, a town park, and a vacant urban lot. The protocol provides a comprehensive assessment of the soil’s ability to perform critical environmental functions at a relatively modest cost, and it helps target management and remediation approaches.

Rising concerns about greenhouse gases, increased fuel prices, and the potential for new high value agricultural products have raised interest in the use of maize stover for bioenergy production. However, residue harvest must be weighed against potential negative impacts on soil quality. This study, conducted in Chazy, NY, evaluated the long-term effects of 32 yr of maize (Zea mays L.) stover harvest vs. stover return on soil quality in the surface layer (5-66 mm) under plow till (PT) and no-till (NT) systems on a Raynham silt loam (coarse-silty, mixed, active, nonacid, mesic Aeric Epiaquept) using physical, chemical, and biological soil properties as soil quality indicators. Twenty-five soil properties were measured, including standard chemical soil tests, aggregate stability (WSA), bulk density, (ρ b ) penetration resistance (PR), saturated hydraulic conductivity (K s ), infiltrability (Infilt), several porosity indicators (aeration pores(PO > 1000), soil water potential = Ψ > -0.36 kPa; air-filled pores at field capacity (PO > 30), Ψ > -10kPa; available water capacity (AWC), -1500 < Ψ < -10 kPa), total organic matter (OM), parasitic (Nem Parasitic ) and beneficial nematode (Nem Beneficial ) populations, decomposition rate (Decomp), potentially mineralizable N (PMN) and easily extractable (EEG) and total glomalin (TG). Only eight indicators were adversely affected by stover harvest, and most of these effects were significant only under NT. Almost all indicators affected by stover removal were affected equally or more adversely by tillage. A total of 15 indicators were adversely affected by tillage. Results of this study suggest that, on a silt loam soil in a temperate climate, long-term stover harvest had lower adverse impacts on soil quality than long-term tillage. Stover harvest appears to be sustainable when practiced under NT management.

Soil quality and health are terms describing similar concepts, but the latter appeals to farmers and crop consultants as part of a holistic approach to soil management. We regard soil health as the integration and optimization of the physical, biological and chemical aspects of soils for improved productivity in an economic and sustainable manner. This paper describes the process used for the selection of soil quality/health indicators that comprise the new Cornell Soil Health Test. Over 1,500 samples collected from controlled research experiments and commercial farms were initially analyzed for 39 potential soil quality indicators. Four physical and four biological indicators were selected based on sensitivity to management, relevance to functional soil processes, ease and cost of sampling, and cost of analysis. Seven chemical indicators were also selected as they are part of the standard soil nutrient test. Soil health test reports were developed to allow for an overall assessment, as well as the identification of specific soil constraints. The new soil health test is being offered on a for-fee basis starting in 2007. In addition, visible near infrared reflectance spectroscopy was evaluated as a possible tool for low-cost soil health assessment. From preliminary analyses, the methodology shows promise for some but not all of the soil quality indicators. In conclusion, an inexpensive soil health test was developed for integrative assessment of the physical, biological, and chemical aspects of soils, thereby facilitating better soil management.

Routine soil analyses provide an approach for assessment and monitoring of soil quality and targeted implementation of management practices, but suitable indicators are mostly undefined. We used three long-term experiments on several soil types where maize (Zea mays L.) was grown under different tillage (no till and plow till), rotation (continuous maize and maize after grass), and harvesting (silage and grain) methods to identify suitable indicators for evaluating soil physical quality. Disturbed and undisturbed soil samples were collected, and laboratory-based analyses were performed for water-stable aggregation, saturated hydraulic conductivity, several pore size parameters, penetration resistance at A = j10 MPa, and bulk density. Sensitivity to management, expense of measurement, measurement consistency, and relevance to critical physical soil processes were used as criteria to evaluate indicator suitability. Indicators varied significantly seasonally and by soil type, and several showed significant differences and trends between management treatments. Small water-stable aggregates (0.25‐2 mm) showed the most consistent and significant treatment differences. Bulk density, available water capacity, and air-filled pores at field capacity (PO 9 30) were also related to treatment effects and had low variability. Penetration resistance and effective porosity (PO 9 0.2) were not sensitive to management practices, whereas aeration pores and saturated hydraulic conductivity were too variable to use as indicators. Several indicators measured on undisturbed cores may be predicted from those measured from disturbed samples using pedotransfer functions. Small water-stable aggregates (0.25‐2 mm), available water capacity, bulk density, and PO 9 30 appear most promising as indicators for routine evaluation and monitoring of soil physical quality. (Soil Science 2007;172:895‐912)

Mathematical models may be used to develop management strategies that optimize the use of nutrients from complex sources such as manure in agriculture. The Precision Nitrogen Management (PNM) model is based on the LEACHN model and a maize N uptake/growth and yield model and focuses on developing more precise N management recommendations. The PNM model was evaluated for simulating drain flow nitrate-nitrogen (NO3-N) in a 3-yr study involving different times of liquid manure application on two soil textural extremes, a clay loam and a loamy sand under maize (Zea mays, L.) production. The model was calibrated for major N transformation rate constants including mineralization, nitrification and denitrification, and its performance was tested using two different calibration scenarios with increasing levels of generalization: (i) separate sets of rate constants for each individual soil type and (ii) a single set of rate constants for both soil types. When calibrated for each manure application treatment for each soil type, the model provided good simulations of monthly and seasonal drain flow NO3-N concentrations. The correlation coefficient (r) and Willmott’s index of agreement (d) ranged from 0.63 to 0.96 and 0.72 to 0.92, respectively. The calibrated model performed reasonably well when rate constant values averaged over manure application treatment for each soil type were used, with r and d values between 0.54 and 0.97, and 0.70 and 0.94, respectively, and greater accuracy for the clay loam soil. When rate constant values were averaged over manure application treatments and soil types, model performance was reasonably accurate for the fall time manure application on the clay loam (r and d of 0.60 and 0.91 and 0.72 and 0.92, respectively) and satisfactory for the spring time on the clay loam and the fall and spring times for the loamy sand soil (r and d between 0.56 and 0.90 and 0.58 and 0.84, respectively). The use of the model for predicting N dynamics under manure-fertilized maize cropping appears promising.

No-tillage in association with row crop production is generally believed to be poorly adapted to fine-textured soils, especially in temperate humid climates. The relative success of conservation tillage may be impacted by changes in soil structure. The objective of this study is to evaluate the performance of reduced tillage systems after rotation from a perennial sod crop. An experiment involving spring and fall moldboard plow till (PT), no-till (NT)/zone till (ZT), and ridge till (RT) under maize (Zea mays L.) production following alfalfa (Medicago sativa L.) was conducted on a Kingsbury clay loam soil (Gleyic Luvisol) in Northern New York. Soil water content, strength and temperature, plant height, leaf area and number, leaf, stem and root biomass, and root distribution were measured during the 1992 and 1993 growing seasons for spring PT and NT, while from 1994 to 1999 only yield measurements were made. Tillage in 1992 occurred under adequately dry conditions, but in 1993 under partially plastic consistency state, resulting in an underconsolidated plow layer. Soil water contents were generally higher for NT than PT in 1992, but equal in 1993. Root proliferation was good in the subsoil although soil strengths were generally above the 2 MPa level, suggesting that penetrometer measurements are not a good indicator of rooting potential in a well-structured soil. Soil strength was higher in both years under NT, and under both tillage treatments was negatively related to soil water content, except in the surface layer where soil penetrability appears mostly affected by aggregate arrangement. NT recorded higher plant heights, leaf area index and leaf numbers in 1993, while PT recorded higher per plant leaf area, stem and root biomass. Roots were generally more abundant under PT than NT at all depths, and were reduced in trafficked inter-row areas. Maize yield was significantly higher under PT in 1992, but similar to NT in 1993. Further yield data from 1994 to 1999 indicate that reduced tillage systems can perform equally or better compared to fall PT on this soil type. Spring PT generally yields lower than fall PT, NT/ZT, and RT. In general, long-term use of reduced tillage systems is economical on well-structured clay loam soils if adequate consideration is given to maintaining soil structure. # 2000 Elsevier Science B.V. All rights reserved.

Computer-based models that simulate soil hydrologic processes and their impacts on crop growth and contaminant transport depend on accurate characterization of soil hydraulic properties. Soil hydraulic properties have numerous sources of variability related to spatial, temporal, and management-related processes. Soil type is considered to be the dominant source of variability, and parameterization is typically based on soil survey databases. This study evaluated the relative significance of other sources of variability: spatial and temporal at multiple scales, and management-related factors. Identical field experiments were conducted for 3 yr. at two sites in New York on clay loam and silt loam soils, and at two sites in Maryland on silt loam and sandy loam soils, all involving replicated plots with plow-till and no-till treatments. Infiltrability was determined from 2054 measurements using parameters, and Campbell's a and b parameters were determined based on water-retention data from 875 soil cores. Variance component analysis showed that differences among the sites were the most important source of variability for a (coefficient of variation, CV = 44%) and b (CV = 23%). Tillage practices were the most important source of variability for infiltrability (CV = 10%). For all properties, temporal variability was more significant than field-scale spatialmore » variability. Temporal and tillage effects were more significant for the medium- and fine-textured soils, and correlated to initial soil water conditions. The parameterization of soil hydraulic properties solely based on soil type may not be appropriate for agricultural lands since soil-management factors are more significant. Sampling procedures should give adequate recognition to soil-management and temporal processes at significant sources of variability to avoid biased results.« less

Intense use of urban soils causes perturbations in soil ecosystem functioning. Construction activities often involve soil removal, compaction by heavy equipment, mixing of topsoil and subsoil materials, etc. Urban soil environments share many of the same properties of soils found in other areas of managed and natural systems. The Cornell Soil Health Test (CSHT) can be used as a tool to evaluate these negative impacts through a holistic soil assessment framework which provides an evaluation of indicators of soil physical and biological and chemical processes. The suite of soil tests in the CSHT measures key soil processes. Land managers use the CSHT to first identify the soil quality functional constraints and then adapt soil management to address identified limitations.

Africa’s agricultural viability and food security depend heavily on its soil quality. However, while approaches to measuring air and water quality are widely established, standardized, publicly-available soil quality assessment protocols are largely non-existent. This chapter describes the process we have used in selecting and developing a set of inexpensive, agronomically meaningful, low-infrastructure-requiring indicators of soil quality (SQ), which make up the Cornell Soil Health Test (CSHT). In 2006, the CSHT was made available to the public in New York State (NYS), United States, similar to the widely available soil nutrient tests. Case studies show the CSHT’s success at measuring constraints in agronomically essential soil processes and differences between management practices in NYS. It thus helps farmers to specifically target management practices to alleviate quantified constraints. Such indicators have the potential to be developed into standardized soil quality tests for use by African agricultural non-governmental and government organizations and larger commercial farmers to better understand agricultural problems related to soil constraints and to develop management solutions. Low cost and infrastructure requirements make these tests excellent tools for numerous low-budget extension and NGO-based experiments established in collaboration with local small farmers, as well as to quantify the status and trends of soil degradation at regional and national scales.

Cadle-Davidson, L., Schindelbeck, R. R., van Es, H. M., Gray, S. M., and Bergstrom, G. C. 2003. Using air pressure cells to evaluate the effect of soil environment on the transmission of soilborne viruses of wheat. Phytopathology 93:1131-1136. An air pressure cell, a laboratory tool that precisely controls soil matric potential, was utilized in a novel approach to investigate the epidemiology and management of soilborne disease. Matric potentials of –1, –5, –20, and –40 kPa were established in cores of field soil infested with Wheat soilborne mosaic virus (WSBMV) and its presumed vector Polymyxa graminis. Equilibrated soil cores were planted to wheat (Triticum aestivum), and after intervals of growth under controlled environment, virus transmission was assessed by serological detection of the virus in washed roots. Transmission occurred at all but the driest soil matric potential tested, –40 kPa, in which only pores with a diameter of 7.4 µm or less were water-filled, possibly obstructing movement of P. graminis zoospores. By starting plants at –40 kPa for 10.5 days and then watering them to conducive matric potential, we found that WSBMV transmission occurred between 12 to 24 h at 15°C, and within 36 h at 20°C. No significant transmission occurred within 96 h at 6.5°C. In contrast, transmission of Wheat spindle streak mosaic virus (WSSMV) did not occur at 15°C (the only transmission temperature tested), suggesting either that WSSMV is unable to establish infection at 15°C or that a different vector is involved. The air pressure cell is a novel tool with many potential applications in research on the epidemiology and management of soilborne pathogens. Applications of the precise environmental control attained through the use of air pressure cells range from assessing the effects of cultural practices on soilborne inoculum to standardized virulence assays for soilborne pathogens to preliminary screens of host resistance and pesticide efficacy.

In studies of erosion, runoff, and infiltration, high soil variability may demand many replicate measurements and rapid, inexpensive methodology. We developed a drop-forming rainfall simulator in which flow through long, coiled capillary drip tubes is controlled by an adjustable Mariotte-type bubbling tube. These rain simulators are inexpensive, rugged, simple to operate, easily transported, and require minimal maintenance. Responses to pressure head and water temperature changes were determined for two simulators using tap water. Flow response to pressure head changes corresponded closely to that predicted by Poiseuille's Law. Response to increasing water temperatures was somewhat less than predicted, due to formation of bubbles in the capillary tubes. Simulators incorporating long, coiled capillary tubes can provide combinations of low flow rates and large drop sizes, or a desired range of flow rates when appropriate drip tube diameters, lengths, and numbers of tubes per unit area are combined.

Honeylocust seedlings (Gleditsia triacanthos L.) were grown in cylinders containing soil adjusted to pH 4, 5 or 6, and harvested every 10 days for 40 days for dry weight and leaf mineral analysis. Total weight of plants grown at pH 4 was less than that of plants grown at pH 5 or 6. Root weight accounted for a greater proportion of total weight in plants grown at pH 4 than in plants grown at pH 5 or 6. Root growth as a function of total plant growth was higher in plants grown at pH 4 than in plants grown at pH 5 or 6, whereas leaf growth as a function of total plant growth was less in plants grown at pH 4 than in plants grown at pH 5 or 6. However, the relationships between root biomass and root length and between leaf biomass and leaf area were the same in all treatments. An analysis of total leaf concentrations of Ca, P, K, Mg, Mn and Al indicated that Al accumulation in leaves was significantly related to a decrease in plant growth at pH 5. A leaf tissue aluminum concentration of 35 microg g(-1) was associated with toxicity symptoms and a 25% reduction in total plant weight.