Crop and Soil Sciences

The development of the theory and construction of combinatorial designs originated with the work of Euler on Latin squares. A Latin square on Ò symbols is an Ò¢Ò matrix (Ò is the order of the Latin square), in which each symbol occurs precisely once in each row and in each column. Several interesting research questions posed by Euler with respect to Latin squares, namely regarding orthogonality properties, were only solved in 1959 . Many other questions concerning Latin squares constructions still remain open today.

If benefits of conservation tillage can be quantified even in the transition year from conventional tillage, growers will more likely integrate practices that maintain or enhance soil quality and productivity. The management of surface residue is an important component of conservation tillage, especially in cool, rainy climates where vegetable growth and yield reductions have been observed when heavy residue is present. Cereal rye (Secale cereale L.), grown until flowering, was killed with glyphosate and was then cut and removed (stubble treatment) or rolled or chopped to form a surface mulch (mulched treatment) before transplanting cabbage. Rolled mulch increased soil wet aggregate stability by 4% and reduced soil penetrometer resistance by up to 0.5 MPa compared with rye stubble treatments in 2003. In 2004, frequent rains saturated soils and may have accelerated the decomposition of chopped mulch, minimizing treatment effects. Rolled mulch reduced soil temperatures by up to 2 8C in 2003, but June transplanting of cabbage probably minimized the impact of soil temperature. Mulched treatments did not delay cabbage maturity or affect head quality characteristics such as color or uniformity. Although rolled mulch reduced cabbage growth by as much as 30% and yield by 21% in 2003, chopped mulch did not affect growth or yield in 2004. Yield reduction may be overcome by killing the rye relatively early in the spring or retaining only the surface stubble; these strategies may maintain or measurably improve soil quality even in the transition year to conservation tillage.

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 ...

The development of the theory and construction of combinatorial designs originated with the work of Euler on Latin squares. A Latin square on symbols is an matrix ( is the order of the Latin square), in which each symbol occurs precisely once in each row and in each column. Several interesting research questions posed by Euler with respect to Latin squares, namely regarding orthogonality properties, were only solved in 1959 [3]. Many other questions concerning Latin squares constructions still remain open today. From the perspective of the Constraint Programing (CP), Artificial Intelligence (AI), and Operations Research (OR) communities, combinatorial design problems are interesting since they possess rich structural properties that are also observed in real-world applications such as scheduling, timetabling, and error correcting codes. Thus, the area of combinatorial designs has been a good source of challenge problems for these research communities. In fact, the study of combinato...

Spatial heterogeneity in fields may affect the outcome of experiments. The conventional randomized allocation of treatments to plots may cause bias and variable precision in the presence of trends (including periodicity) and spatial autocorrelation. Agricultural scientists appear to mostly use conventional experimental designs that are susceptible to adverse affects from field variability. The objectives of this research were to (i) quantify the use of different experimental designs in agronomic field experiments, and (ii) develop spatially-balanced designs that are insensitive to the effects of both trends and spatial autocorrelation. A review was performed of all research efforts reported in Volumes 93-95 of the Agronomy Journal and the frequency of various experimental designs was determined. It showed that the vast majority (96.7%) of agronomic field experiments are implemented through Randomized Complete Block (RCB) designs. The method of simulated annealing was used to develop Spatially-Balanced Complete Block (SBCB) designs based on two objective functions: promoting spatial balance among treatment contrasts, and disallowing treatments to occur in the same position in different blocks, when possible. SBCB designs were successfully developed for designs up to 15 treatments and 15 replications. Square SBCB designs were realized as Latin Squares, and perfect spatial balance was obtained when feasible. SBCB designs are simple to implement, are analyzed through conventional ANOVAs, and provide protection against the adverse effects of spatial heterogeneity, while randomized allocation of treatments still ensures against user bias.

This study was conducted to compare various orchard groundcover management systems (GMSs)—including a crownvetch “living mulch” (CNVCH), close-mowed (MWSOD) and chemically growth-regulated (GRSOD) sodgrasses, pre-emergence (NDPQT) and two widths of post-emergence (GLY1.5 and GLY2.5) herbicides, hay-straw mulch (STMCH), and monthly rototillage (tilled)—during the first 6 years in a newly established apple (Malus domestica Borkh.) planting. Mean soil water potential at 5 to 35 cm deep varied substantially among treatments each summer, and treatment × year interactions were observed. During most growing seasons from 1986 to 1991, soil water availability trends were STMCH > NDPQT > GLY2.5 > GLY1.5 > tilled > GRSOD > MWSOD > CNVCH. Soil organic matter content increased under STMCH, CNVCH, and MWSOD and decreased under NDPQT and tilled treatments. Water infiltration and saturated hydraulic conductivity after 4 years were lower under NDPQT and tilled, and soil under ST...

Background and Aims: Environmental variables within vineyards are spatially correlated, impacting the economic efficiency of cultural practices and accuracy of viticultural studies that utilise random sampling. This study aimed to test the performance of non-random sampling protocols that account for known spatial structures ('spatially explicit protocols') in reducing sampling requirements versus random sampling. Methods and Results: Canopy microclimate data were collected across multiple sites/seasons/training systems. Autocorrelation was found in all systems, with a periodicity generally corresponding to vine spacing. Three spatially explicit sampling models were developed to optimise the balance between minimum sample sizes and maximum fit to a known probability density function. A globally optimised explicit sampling (GOES) model, which performed multivariate optimisation to determine best-case sampling locations for measuring fruit exposure, reduced fruit cluster sample size requirements versus random sampling by up to 60%. Two stratified sampling protocols were derived from GOES solutions. Spatially weighted template sampling (STS) reduced sampling requirements up to 24% when based on probabilistic panel weighting (PW), and up to 21% when preferentially selecting specific locations within canopy architecture (AW). Conclusions: GOES, PW STS and AW STS each reduced required sample size versus random sampling. Comparative analyses suggested that optimal sampling strategies should simultaneously account for spatial variability at multiple scales. Significance of the Study: This study demonstrates that dynamically optimised sampling can decrease sample sizes required by researchers and/or wineries.

Nitrogen decision making for maize (Zea mays L.) is difficult because of seasonal weather fluctuations. New tools have emerged based on dynamic simulation models that account for weather variability. We evaluated the performance of the Adapt-N tool relative to North Carolina's Realistic Yield Expectation (RYE) framework through six multi-N rate maize plot trials in three physiographic regions and 38 strip trials on commercial farms in the coastal plain. Yield response and profit were evaluated with quadratic plateau (QP) response curves. The RYE framework generally estimated the agronomic optimum N rate (AONR) well, as did Adapt-N after modification to account for high soil organic matter (SOM) and C/N ratio mineral-organic coastal plain soil; there was, however, much greater site variability with Adapt-N. Adapt-N was sensitive to SOM content inputs, which varied based on method and laboratory. The RYE provided overall higher dollar return than Adapt-N; Adapt-N returns varied based on SOM and yield goal inputs, since they strongly impact N rate recommendations. In the on-farm strip-trials, 58% of yields were not statistically different between lower N rates and other treatments including Adapt-N. On average, Adapt-N performed similar to grower-consultant practice with modest tradeoffs between reduced N rates and yield. Adapt-N recommendations and grower rates yielded higher than RYE and required more N. Overall, the RYE approach performed better than Adapt-N in N research farm trials; in on-farm strip trials Adapt-N performed similarly to grower-consultant practices and in various cases provided economical yield increases over RYE.

As a soil amendment, cattle manure enhances soil mineral N content if managed correctly. Manure management varies among smallholder Kenyan farms, yet the quality of manure produced by different methods has not been assessed. This study examined the effects of storage method on the manure N composition and degradability in the soil. Nitrogen composition of manure from cattle fed high and low quality diets, stored under different containment, shading, and manure addition methods was monitored for 30 days. Manure aged 30 days was buried in soil in large-and small mesh litterbags. The disappearance of organic N was monitored over 112 days. Time in storage (P < 0.03) and farm of origin (P < 0.0001) were the only variables to influence manure organic N content. Origin (P < 0.04) and time in storage (P < 0.0001) were also the only variables that affected manure mineral N content. Manure N derived from cows fed a higher quality food (Medium quality manure) disappeared faster than manure N derived from cows fed a lower quality food (Low quality manure). More N may be available for uptake by plants during one growing season if manure from better-fed cattle is used as a soil amendment.

INTRODUCTION Remote sensing is an important tool in agriculture and soil evaluation, contributing to the collection novel information as a non-destructive, quick and low-cost technique 1. Many conventional soil analytical techniques are used in an attempt to establish the relationship between soil physical and chemical properties and individual soil components, often disregarding their complex, multi-component interactions 2. Standard procedures for measuring soil properties being time-consuming and expensive, much attention is given to possible alternatives such as near infrared reflectance spectroscopy (NIRS). Near infrared reflectance spectroscopy is a non-destructive analytical technique for studying interactions between incident light and a material's surface 3. Near infrared reflectance spectroscopy is a physical non-destructive, rapid, reproducible and low-cost method that characterizes materials according to their reflectance in the wavelength range between 350 and 2500 nm 2,4-7. Infrared spectroscopy in the near and mid-infrared ranges has been found to be useful in providing rapid, cheap and relatively accurate predictions for a number of soil properties 2,4-7 .

Timing of manure application affects N leaching. This 3-yr study quantified N losses from liquid manure application on two soils, a Muskellunge clay loam and a Stafford loamy sand, as affected by cropping system and timing of application. Dairy manure was applied at an annual rate of 93 800 L ha 21 on replicated drained plots under continuous maize (Zea mays L.) in early fall, late fall, early spring, and as a split application in early and late spring. Variable rates of supplemental sidedress N fertilizer were applied as needed. Manure was applied on orchardgrass (Dactylis glomerata L.) in split applications in early fall and late spring, and early and late spring, with supplemental N fertilizer topdressed as NH 4 NO 3 in early spring at 75 kg N ha 21. Drain water was sampled at least weekly when lines were flowing. Three-year FWM (flow-weighted mean) NO 3-N concentrations on loamy sand soil averaged 2.5 times higher (12.7 mg L 21) than those on clay loam plots (5.2 mg L 21), and those for fall applications on maize-cropped land averaged .10 mg L 21 on the clay loam and .20 mg L 21 on the loamy sand. Nitrate-N concentrations among application seasons followed the pattern early fall. late fall. early spring 5 early 1 late spring. For grass, average NO 3-N concentrations from manure application remained well below 10 mg L 21. Fall manure applications on maize show high NO 3-N leaching risks, especially on sandy soils, and manure applications on grass pose minimal leaching concern.

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 (NO 3-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 NO 3-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.

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 exte...

Several potential sources of information exist to support precision management of crop inputs. This study evaluated soil test data, bare-soil remote sensing imagery and yield monitor information for their potential contributions to precision management of maize (Zea mays L.). Data were collected from five farmer-managed fields in Central New York in 1999, 2000, and 2001. Geostatistical techniques were used to analyze the spatial structure of soil fertility (pH, P, K, NO 3 and organic matter content) and yield variables (yield, hybrid response and N fertilization response), while remote sensing imagery was processed using principal component analysis. Geographic information system (GIS) spatial data processing and correlation analyses were used to evaluate relationships in the data. Organic matter content, pH, P, and K were highly consistent over time and showed high to moderate levels of spatial autocorrelation, suggesting that grid soil sampling at 2.5-5.5 ha scale may be used as a basis for defining fertility management zones. Soil nitrate levels were strongly influenced by seasonal weather conditions and showed low potential for site-specific N management. Aerial image data were correlated to soil organic matter content and in some cases to yield, mainly through the effect of drainage patterns. Aerial image data were not well correlated with soil fertility indicators, and therefore were not useful for defining fertility management zones. Yield response to hybrid selection and nitrogen fertilization rates were highly variable among years, and showed little justification for site-specific management. In conclusion, we recommend grid-based management of lime, P, and K, but no justification existed within our limited study area for site-specific N or hybrid management.

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 capa...

A compact, two-stage nanomanipulator was designed and built for use inside a scanning electron microscope. It consists of a fine stage employing piezostacks that provide a 15 m range in three dimensions and a coarse stage based on commercially available stick-slip motors. Besides the fabrication of enhanced probes for scanning probe microscopy and the enhancement of electron field emitters, other novel manipulation processes were developed, such as locating, picking up, and positioning small nanostructures with an accuracy of ϳ10 nm. In combination with in situ I-V experiments, welding, and etching, this results in a multipurpose nanofactory, enabling a new range of experiments.

Nitrogen dynamics in soils are affected by spatial and temporal processes. Drainage class is generally regarded to be the most signi®cant 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.) ®eld. 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 ®eld-averaged economic optimum N rates had a range of 65 kg ha À1 with lower rates being associated with years with low early-season precipitation. A calibrated LEACHMN model and site-speci®c 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 À1 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 denitri®cation. It is concluded that limited bene®ts may be gained from spatially variable N applications within ®elds 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.

No-tillage in association with row crop production is generally believed to be poorly adapted to ®ne-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 traf®cked inter-row areas. Maize yield was signi®cantly 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.

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 s...