H.M. van Es

Soil and maize response to plow and no-tillage after alfalfa-to-maize conversion on a clay loam soil in New York

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.

Spatial and temporal processes affecting nitrogen availability at the landscape scale

Nitrogen dynamics in soils are affected by spatial and temporal processes. Drainage class is generally regarded to be the most significant source of variability for N in temperate humid climates. A 5-year study was conducted including four rates of N fertilizer and three drainage classes within a 15 ha maize (Zea mays L.) field. Variance component analysis showed that N response was minimally affected by drainage class, but showed strong yearly variations, apparently related to early-season precipitation. Annual field-averaged economic optimum N rates had a range of 65 kg ha ˇ1 with lower rates being associated with years with low early-season precipitation. A calibrated LEACHMN model and site-specific weather data were used to evaluate the effects of early-season weather conditions on N rate and availability. During wet years, soil N availability was reduced by approximately 35‐50 kg ha ˇ1 compared to dry years, largely independent of drainage class. For well-drained soils, most losses were attributed to leaching (especially in years with wet early-season), while poorly drained soils mainly experienced denitrification. It is concluded that limited benefits may be gained from spatially variable N applications within fields based on drainage class or soil type, but considerable economic and environmental gains are possible from yearly adjustment of supplemental N rates based on model simulations of N dynamics using information on early-season weather conditions. # 2001 Elsevier Science B.V. All rights reserved.

Use of an integrative soil health test for evaluation of soil management impacts.

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 mays L.)–soybean ( Glycine max L.) 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.

N fate and transport under variable cropping history and fertilizer rate on loamy sand and clay loam soils: I. Calibration of the LEACHMN model

The need for efficient use of agricultural chemicals and their potential adverse impact on critical water resources have increased the use of simulation models of the soil and plant system. Nevertheless, there is currently little or no agreement concerning model validity and applicability in varied soils and environments. The research version of LEACHMN (the N subroutine of LEACHM) was calibrated using field data including soil physical, hydraulic, and chemical properties, and maize (Zea mays L.) N uptake collected from a 3-yr nitrate leaching experiment. The field site consisted of plot-size lysimeters on clay loam and loamy sand soils with N fertilizer rates of 22, 100 and 134 kg N ha−1. The calibration involved adjusting nitrification, denitrification, and volatilization rate constants to optimize the fit between predicted and measured data. When calibrated for each treatment-year combination and soil type, the model simulations of soil profile NO3–N distribution were generally successful. The N transformation rate constants yielded by the calibration efforts were similar or close to those used in other model simulation studies. At both sites, the calibrated rate constants for the first year (following sod plowdown) were different from those for the subsequent two years. Denitrification rate constants were consistently higher for the clay site than for the sand site, while the nitrification rate constants were lower. N rate of application appeared not to affect the rate constants within each year-site combination, suggesting that cropping history and soil type had the greatest effect on N transformation rates.

Growth development and yield of maize under three tillage systems in the northeastern U.S.A.

Abstract Cool spring temperatures are a major constraint to maize ( Zea mays L.) production in northern regions of the U.S.A., and a no-till (NT) system intensifies the problem because residue on the surface further decreases soil temperature. Ridge tillage (RT), because of the configuration of the ridge and the removal of most of the residue from the seed zone during the planting operation, may alleviate this problem. Field experiments were established in New York on a drained and undrained silt loam soil (fine-loamy, mixed, nonacid, mesic Aeric Haplaquept) to examine the influence of a fall-plowed, or conventional tillage, system (CT), NT, and RT on soil temperature growing degree days (GDD) and subsequent growth, development, and yield of maize in continuous production. Soil GDD averaged about 35–40 GDD less under NT during the first 35 days after emergence, which resulted in a consistent three-day delay in silking and a lower maximum leaf area index (LAI) and crop growth rate (CGR). Under drained conditions, grain yields under NT averaged 10% lower than CT (8.68 and 9.60 Mg ha −1 , respectively). In two of the three years, however, higher CGR under NT duringv the grain-filling period resulted in the same total phytomass and grain yields as under CT. Soil GDD averaged about 10 GDD more under RT than under CT and the development of maize under RT and CT was essentially the same. Nevertheless, under drained conditions, the growth of maize under RT was slightly slower than under CT and grain yields (9.05 Mg ha −1 ) averaged 5% lower. In the undrained experiment, where some flooding occurred in two of the three years, grain yields were significantly higher under RT than under CT and NT (7.92, 7.09, and 7.19 Mg ha −1 , respectively). In 1988, when a two-day flooding period occured shortly after emergence, the configuration of the ridge reduced the duration of surface flooding from two days to one day, which resulted in increased plant survival, faster growth and development, and higher grain yields (7.36, 5.79, and 5.60 under RT, CT, and NT, respectively). In conclusion, RT appears to be a well adapted conservation tillage system for continuous maize production in northern regions, especially on soils that flood periodically.

N rate and transport under variable cropping history and fertilizer rate on loamy sand and clay loam soils: II. Performance of LEACHMN using different calibration scenarios

Testing of existing agronomic models is needed to ensure their validity and applicability to different soils, cropping systems and environments. Data collected from a 3-year field experiment of maize (zea mays L.) on a loamy sand and a clay loam soil were used to validate the research version of the LEACHMN model for water flow and N fate and transport. Three calibration scenarios with increasing levels of generalization for transformation rate coefficients were used based on: (i) each year, treatment and soil type (ii) 3-year average values for each treatment and soil type, and (iii) average over years and soil types. Model accuracy was tested using both graphical and statistical methods including 1:1 scale plot, root mean square error and normalized root mean square error, and correlation coefficient values. The model accurately predicted drainage water flow rate and volume under both sites. Calibrated N transformation rate constants for each treatment, year and soil type provided satisfactory predictions of growing season cumulative NO3–N leaching losses, and accurate predictions of growing season cumulative maize N uptake at both sites. The use of 3-year average rate constant values for each site resulted in fairly satisfactory predictions of NO3–N leaching losses on the clay loam site, but inaccurate predictions on the loamy sand site. The model provided accurate predictions of cumulative maize N uptake for both sites. Using the rate constant values averaged over years and soil types resulted mostly in inaccurate predictions. Use of year and soil type-specific N rate coefficients results in accurate LEACHMN predictions of N leaching and maize N uptake. When rate coefficients are generalized over years for each soil type, satisfactory model predictions may be expected when N dynamics are not strongly affected by yearly variations in organic N inputs.

Spatial Analysis of Maize Response to Nitrogen Fertilizer in Central New York

An increasing number of farmers are considering the use of site-specific nitrogen (N) applications to maize (Zea mays L.) as a way of maximizing yield potential while minimizing fertilizer cost. The objectives of this 3-years experiment were to evaluate the spatial structure of yield response to N fertilizer and investigate the potential for site-specific N management under maize production in New York. Four experimental N rates (50, 110, 160, or 220 kg ha∧1), two tillage systems (chisel till and zone-till) and two crop rotations (maize•maize and maize•soybean (Glycine max L.)) were superimposed over a 12 ha field in central New York State with a complex of Honeoye-Lima, Kendaia, and Lima soils ranging from moderately well to poorly drained soils. Pre-sidedress soil nitrate tests (PSNT) showed significant spatial structure but did not conform to that for crop N response, indicating that N fertilizer recommendations based on PSNT results cannot be simply applied in a site-specific management approach. Optimal N rate varied from 110 kg ha ∧1 for the dry years 1999 and 2000 to 220 kg ha∧1 for 1998, with a warm wet spring. Tillage treatments were generally comparable in N response. Spatial yield response analysis showed limited field-scale regionalization of both yield and profit response to N, suggesting that site-specific application of nitrogen is impractical. The greatest source of variability in N requirements was observed with the annual effects of weather, and presents a greater potential for precise N application than site-specific application. Annual variations in optimum N rate were not related to annual yield differences and yield potential itself does not appear to be a good predictor of N needs.

Quantification and modeling of macropore drainage

Abstract A series of experiments on undisturbed soil columns, followed by interpretation using simulation modeling, were conducted to estimate the influence of soil structure upon macroporosity and water flow. Four large soil columns taken from Niagara silt loam and Rhinebeck silty clay loam profiles were placed on a grid sampler to obtain 25 subsample outflow measurements per column. Columns were saturated from the bottom and saturated hydraulic conductivity was measured under shallow ponding. Columns were then gravity drained while outflow was collected. Saturated hydraulic conductivity and drainage volume were lognormally distributed over the column bottom area. Drainage volumes were not significantly different among columns or soils, at the 5% level. Analysis of the drainage rates of the columns indicated that soil texture influenced macropore geometry by controlling soil structure and plant rooting. Geometric scaling factors from the distribution of saturated hydraulic conductivity, applied to conductivity and potential in simulations of column drainage, did not reproduce the observed distribution of drainage volume. When additional normally-distributed coefficients were applied to porosity, the simulated drainage distributions were not significantly different from observed drainage distributions, at the 5% level.

Developing Standard Protocols for Soil Quality Monitoring and Assessment

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.

Using Air Pressure Cells to Evaluate the Effect of Soil Environment on the Transmission of Soilborne Viruses of Wheat

ABSTRACT 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 mum 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 degrees C, and within 36 h at 20 degrees C. No significant transmission occurred within 96 h at 6.5 degrees C. In contrast, transmission of Wheat spindle streak mosaic virus (WSSMV) did not occur at 15 degrees C (the only transmission temperature tested), suggesting either that WSSMV is unable to establish infection at 15 degrees 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.