New England Plant, Soil and Water Research Laboratory

Soil quality assessment could become more standardized with the development of a simple, rapid, and reliable method for quantifying potential soil biological activity. We evaluated the flush of CO 2 following rewetting of dried soil under standard laboratory conditions as a method to estimate an active organic matter fraction. The flush of CO 2 following rewetting of dried soil (3 d incubation at ≈50% water‐filled pore space and 25°C) was assessed for 20 soil series containing a wide range of organic C (20 ± 13 g kg −1 ) from Alberta–British Columbia, Maine, Texas, and Georgia. This flush of CO 2 explained 97% of the variability in cumulative C mineralization during , 86% of the variability in soil microbial biomass , and 67% of the variability in net N mineralization during Accounting for geographical differences in mean annual temperature and precipitation, which could affect soil organic matter quality, further improved relationships between the flush of CO 2 and active, passive, and total C and N pools. Measuring the flush of CO 2 following rewetting of dried soil may have value for routine soil testing of biological soil quality because it (i) is an incubation procedure patterned after natural occurrences in most soils, (ii) exhibits strong overall relationships with active organic pools, (iii) shows relatively minor changes in relationships with active organic pools that may be due to climatic variables, (iv) has a simple setup with minimal equipment requirements, and (v) has rapid analysis time.

Soil health has been defined as the capacity of soil to function as a vital living system to sustain biological productivity, maintain environmental quality, and promote plant, animal, and human health. Building and maintaining soil health are essential to agricultural sustainability and ecosystem function. Management practices that promote soil health, including the use of crop rotations, cover crops and green manures, organic amendments, and conservation tillage, also have generally positive effects on the management of soilborne diseases through a number of potential mechanisms, including increasing soil microbial biomass, activity, and diversity, resulting in greater biological suppression of pathogens and diseases. However, there also may be particular disease issues associated with some soil health management practices. In this review, research and progress made over the past twenty years regarding soil health, sustainability, and soil health management practices, with an emphasis on their implications for and effects on plant disease and disease management strategies, are summarized.

Agricultural production in the United States is undergoing marked changes due to rapid shifts in consumer demands, input costs, and concerns for food safety and environmental impact. Agricultural production systems are comprised of multidimensional components and drivers that interact in complex ways to influence production sustainability. In a mixed-methods approach, we combine qualitative and quantitative data to develop and simulate a system dynamics model that explores the systemic interaction of these drivers on the economic, environmental and social sustainability of agricultural production. We then use this model to evaluate the role of each driver in determining the differences in sustainability between three distinct production systems: crops only, livestock only, and an integrated crops and livestock system. The result from these modelling efforts found that the greatest potential for sustainability existed with the crops only production system. While this study presents a stand-alone contribution to sector knowledge and practice, it encourages future research in this sector that employs similar systems-based methods to enable more sustainable practices and policies within agricultural production.

Phytic acid (inositol hexaphosphoric acid, IP6) has long been recognized as the predominant organic P form in soil and animal manure. Whereas many studies have investigated the wet chemistry of IP6, there is little information on the characterization of solid metal IP6 compounds. This information is essential for further understanding and assessing the chemical behavior of IP6 in diverse soil-plant-water ecosystems. As the first step in full characterization, we synthesized eight metal phytate compounds and investigated their structural features using Fourier transform infrared spectroscopy (FT-IR). The absorption features from 900 to 1200 cm(-1) in FT-IR could be used to identify these phytates as: (i) light divalent metal (Ca and Mg) compounds with a sharp band and a broad band, (ii) heavy divalent metal (Cu and Mn) compounds with splitting broad bands, and (iii) trivalent metal (Al and Fe) compounds with a broad band and a shoulder band. Three different types of chemical structures of metal-phytate compounds were presented based on the FT-IR information. We further demonstrated that metal orthophosphates possessed different FT-IR spectral characteristics from their IP6 counterparts. The unique spectral features of metal phytates from 1000 to 700 cm(-1) could be used to distinguish phytate compounds from metal phosphate compounds. Thus, FT-IR analysis after fine tuning could provide an analytical tool to investigate the basic metal phytate chemistry in molecular levels, such as the competitive interactions between phosphate and phytate with a specific metal ion, and the conversion (or hydrolysis) of metal phytate to metal phosphate under various conditions.

We describe the establishment and analysis of a genus-wide comparative framework composed of 12 bacterial artificial chromosome fingerprint and end-sequenced physical maps representing the 10 genome types of Oryza aligned to the O. sativa ssp. japonica reference genome sequence. Over 932 Mb of end sequence was analyzed for repeats, simple sequence repeats, miRNA and single nucleotide variations, providing the most extensive analysis of Oryza sequence to date.

Because humic substances are involved in many processes in soils and natural waters, characterization of phosphorus (P) associated with humic substances may shed light on the function of natural organic matter in P cycling and nutrition. In this study, we investigated the spectral features and potential availability of P in the International Humic Substance Society (IHSS) Elliott Soil humic acid standard (EHa), Elliott soil fulvic acid standard II (EFa), Waskish peat humic acid reference (WHa), and Waskish peat fulvic acid reference (WFa) by fluorescence spectroscopy, Fourier‐transform infrared spectroscopy (FT‐IR), solution 31 P nuclear magnetic resonance (NMR), 3‐phytase incubation, and UV irradiation. We observed more similar spectral features between EHa and EFa as well as between WHa and WFa than between the two humic acids or two fulvic acids themselves. Phosphorus in WHa and WFa was mainly present in the orthophosphate form. However, only about 5% was water soluble. After treatment by both UV irradiation and enzymatic hydrolysis, soluble orthophosphate increased to 17% of the P in WHa, and 10% of the P in WFa. Thus, it appears that a large portion of P in Waskish peat humic substances was not labile for plant uptake. On the other hand, both orthophosphate and organic phosphate were present in EHa and EFa. Treatment by both UV irradiation and enzymatic hydrolysis increased soluble orthophosphate to 67% of the P in EHa and 52% of the P in EFa, indicating that more P in Elliott soil humic substances was potentially bioavailable. Our results demonstrated that source (soil vs. peat) was a more important factor than organic matter fraction (humic acid vs. fulvic acid) with respect to the forms and lability of P in these humic substances. This work represents a much more complete characterization of humic substance‐bound P than previously reported in the literature, thus providing a comprehensive approach for improved understanding of P cycling in relation to ecosystem function.

Predictive tools are needed to better match N release from manure with crop demand. Growing degree days (GDD) have been successfully used to predict N release from crop residues and other amendments. A 112‐d incubation experiment was conducted at 10, 17, and 24°C to evaluate GDD (0°C base temperature) predictions of N transformations from beef ( Bos taurus ), dairy, poultry ( Gallus gallus ), and swine ( Sus scrofa ) manure. Manure was incorporated at rates estimated to provide 150 kg N ha −1 (or 75 mg N kg −1 soil). Soil NO 3 and NH 4 concentrations were determined at weekly or biweekly intervals. The rate of NO 3 accumulation increased with increasing temperature, and could be predicted across temperature regimes using GDD. This predictive ability could be generalized across dairy, poultry, and swine manures using an exponential equation, , while N was immobilized by incorporation of beef manure. The disappearance of NH 4 was a linear function of time and of GDD. A single predictive equation was sufficient for dairy, poultry, and swine manures, in the form , with soil NH 4 reaching zero at ≈350 GDD. These laboratory data indicate that GDD can be used for predicting NO 3 accumulation and NH 4 disappearance from a range of livestock manures. If successfully extended to the field, this predictive capability may allow for improved management of N from animal manures.

Solid-state spectroscopic techniques, including Fourier transform infrared (FT-IR) and solid-state 31P magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopies, are powerful tools for evaluating metal speciation and transformation mechanisms of P compounds in soil, animal manure, and other environment samples. These spectroscopic studies generally rely on the reference spectra of model compounds. However, such reference information is limited, especially for metal phytate compounds, which are an important component of many samples (e.g., 60-80% of soil organic P). In this study, we used solid-state FT-IR and 31P MAS NMR to examine metal phytates and their orthophosphate counterparts, as well as several pyrophosphates and polyphosphates. Comparisons of the FT-IR spectra of metal orthophosphates and phytates demonstrated distinct characteristics and differences. The triplet-peak feature in the 790- to 900-cm−1 range could be used to distinguish metal phytates from other P compounds that contained one or no peak in the same range. FT-IR spectral features centered at 1100 cm−1 (i.e., broad or splitting multiple peaks) could distinguish among different metal phytate compounds. We observed that the solid-state 31P NMR peaks of phytate compounds were broad, whereas those of inorganic P compounds were much sharper. We propose that the same attention should be paid to spinning sidebands as on the main peaks, because the features of spinning sidebands were unique for some P compounds. Finally, our observations indicated that wetting samples could change both intensity and position of chemical shifts and spinning sidebands, thus keeping samples dry is necessary to obtain repeatable and high-quality solid-state 31P MAS NMR spectra. The solid-state FT-IR and 31P NMR reference spectra established in this work may help in basic and applied environmental soil P studies by the two advanced spectroscopic technologies.

Knowledge of the P forms in poultry litter (PL) and their transformations in soil will help improve our understanding of the long‐term role of P in eutrophication. In this study, samples of PL and pasture soils with and without 20 yr of PL application were sequentially extracted to separate P into H 2 O, 0.5 mol L −1 NaHCO 3 , 0.1 mol L −1 NaOH, and 1 mol L −1 HCl fractions. After appropriate dilution and pH adjustment, the fractions were incubated in the presence of orthophosphate‐releasing enzymes. Cross‐examination of the solution 31 P nuclear magnetic resonance spectra of the enzymatically treated and untreated fractions revealed that the peaks of organic P (P o ) species of the enzymatically treated fractions became very weak or disappeared, confirming enzymatic hydrolysis of P o in the untreated fractions. Although the majority of P in the NaOH and HCl fractions of PL was in organic forms, these stable P o forms could be subjected to enzymatic hydrolysis after being applied to soil, an occurrence that was supported by the soil P data. Compared with soil without litter applied, 20 yr of PL application increased the pools of both labile and stable inorganic P in the soil; however, repeated application of PL did not lead to a significant accumulation of hydrolyzable P o in NaOH and HCl fractions, indicating that the stable P o must have been converted to other forms. The transformation of stable PL P o observed in this study could be an important mechanism for maintaining a balance between labile and immobile P in soils.

During the past 50 yr, we have witnessed a revolution in the science of plant breeding, genetics, and cytology, and its impact on human lives (e.g., the Green Revolution). Because of increased productivity, breeding objectives evolved from predominantly improving yield to include greater quality and value‐added traits. The discovery of the chemical nature of deoxyribonucleic acid (DNA), coupled with Mendelian genetics led to the refinement of quantitative genetics, the robust use of molecular markers, and transgenic crop plants. Cytogenetics elucidated the physical structure of chromosomes, aided trait and molecular mapping, and greatly enhanced the exploitation of genetic variation from wild relatives, as have transgenes and mutations. The fundamental process of selection has been improved by a better understanding of gene action, when to select, and better methods to select plants and analyze their relationship to the environments in which they grow. Single‐seed descent plant breeding methods were popularized and evolved to doubled haploid breeding. Plant breeding, genetics, and cytology remain impact sciences that will continue to improve lives as part of the Evergreen Revolution.

Both enzymatic hydrolysis and solution (31)P nuclear magnetic resonance (NMR) spectroscopy have been used to characterize P compounds in animal manures. In this study, we comparatively investigated P forms in 0.25 M NaOH/0.05 M EDTA extracts of dairy and poultry manures by the two methods. For the dairy manure, enzymatic hydrolysis revealed that the majority of extracted P was inorganic P (56%), with 10% phytate-like P, 9% simple monoester P, 6% polynucleotide-like P, and 18% non-hydrolyzable P. Similar results were obtained by NMR spectroscopy, which showed that inorganic P was the major P fraction (64-73%), followed by 6% phytic acid, 14 to 22% other monoesters, and 7% phosphodiesters. In the poultry manure, enzymatic hydrolysis showed that inorganic P was the largest fraction (71%), followed by 15% phytate-like P and 1% other monoesters, and 3% polynucleotide-like P. NMR spectroscopy revealed that orthophosphate was 51 to 63% of extracted P, phytic acid 24 to 33%, other phosphomonoesters 6 to 12%, and phospholipids and DNA 2% each. Drying process increased orthophosphate (8.4% of total P) in dairy manure, but decreased orthophosphate (13.3% of total P) in poultry manure, suggesting that drying treatment caused the hydrolysis of some organic P to orthophosphate in dairy manure, but less recovery of orthophosphate in poultry manure. Comparison of these data indicates that the distribution patterns of major P forms in animal manure determined by the two methods were similar. Researchers can utilize the method that best fits their specific research goals or use both methods to obtain a full spectrum of manure P characterization.

Abstract Currently accepted pedotransfer functions show negligible effect of management‐induced changes to soil organic carbon (SOC) on plant available water holding capacity (θ AWHC ), while some studies show the ability to substantially increase θ AWHC through management. The Soil Health Institute's North America Project to Evaluate Soil Health Measurements measured water content at field capacity using intact soil cores across 124 long‐term research sites that contained increases in SOC as a result of management treatments such as reduced tillage and cover cropping. Pedotransfer functions were created for volumetric water content at field capacity (θ FC ) and permanent wilting point (θ PWP ). New pedotransfer functions had predictions of θ AWHC that were similarly accurate compared with Saxton and Rawls when tested on samples from the National Soil Characterization database. Further, the new pedotransfer functions showed substantial effects of soil calcareousness and SOC on θ AWHC . For an increase in SOC of 10 g kg –1 (1%) in noncalcareous soils, an average increase in θ AWHC of 3.0 mm 100 mm –1 soil (0.03 m 3 m –3 ) on average across all soil texture classes was found. This SOC related increase in θ AWHC is about double previous estimates. Calcareous soils had an increase in θ AWHC of 1.2 mm 100 mm –1 soil associated with a 10 g kg –1 increase in SOC, across all soil texture classes. New equations can aid in quantifying benefits of soil management practices that increase SOC and can be used to model the effect of changes in management on drought resilience.

Information on the chemical composition of sediment phosphorus (P) is fundamental to understanding P dynamics and eutrophication in lake ecosystems. In this study, the surface (10 cm) sediments were collected from seven lakes representing two contrasting ecological areas in China: the middle and lower reaches of Yangtze River region and the Southwestern China Plateau. Phosphorus in these sediments was extracted by NaOH-EDTA and characterized by solution 31P nuclear magnetic resonance spectroscopy. Results show that P in the extracts was dominated by inorganic orthophosphate (76.7-97.4% of the extracted P) and orthophosphate monoesters (1.8-14.3%), with smaller amounts of orthophosphate diesters (0.4-8.9%), pyrophosphate (0.1-0.7%), and phosphonates (0.1-0.2%). The relative abundance of orthophosphate was higher in hypertrophic and shallow lake sediments than in eutrophic and mesotrophic and deep lake sediments, whereas the relative abundance of orthophosphate monoesters was the opposite. These observations suggested that the relative abundance of the two types of P forms in sediments might be related to the degree of lake eutrophication.

Accurately characterizing phosphorus (P) forms is a prerequisite to developing effective remediation strategies to minimize the adverse environmental impact of agricultural expansion. Modified or unmodified Hedley sequential fractionation procedures have been widely used for characterizing P forms in soil, animal manure, and biosolids. Hydrochloric acid (HCl) fractions in these procedures have often been assumed to contain no organic P. As a result, many researchers for the last two decades have measured concentrations of inorganic P in HCl fractions without measuring organic P. In this study, we measured colorimetrically concentrations of inorganic P in untreated (control) HCl fractions after 3‐phytase incubation or oxidative autoclaving of these fractions. Phosphorus concentrations in some samples were also determined by inductively coupled plasma optical emission spectroscopy. The increases in measured P concentrations, compared with the controls, were attributed to organic P in these fractions. Data for 15 soil and eight manure samples indicated that, although HCl fractions of some samples contained negligible amounts of organic P, others contained significant amounts of organic P. The concentrations of organic P were greater than inorganic P in one soil sample and two manure samples. We recommend that organic P in HCl fractions be measured experimentally to determine whether the HCl fraction contains inorganic and organic P. Identification of possible organic P species contained in HCl fractions of the Hedley sequential fractionation schemes would provide more accurate and comprehensive knowledge of the fates and interchanges of P forms in soil and animal manure under various environmental conditions.

Organic dairy production has increased rapidly in recent years. Organic dairy cows (Bos taurus) generally eat different diets than their conventional counterparts. Although these differences could impact availability, utilization, and cycling of manure nutrients, little such information is available to aid organic dairy farmers in making nutrient and manure management decisions. In this study, we comparatively characterized P in organic and conventional dairy manure using solution and solid state (31)P NMR spectroscopic techniques. Phosphorus in both types of dairy manure was extracted with water, Na acetate buffer (100 mmol L(-1), pH 5.0) plus 20 mg Na dithionite mL(-1), or 0.025 mol L(-1) NaOH with 50 mmolL(-1) EDTA. Solution NMR analysis revealed that organic dairy manure contained about 10% more inorganic phosphate than conventional dairy manure. Whereas organic dairy manure did contain slightly more phytate P, it contained 30 to 50% less monoester P than conventional dairy manure. Solid state NMR spectroscopy revealed that mono-, di-, and trivalent metal P species with different stabilities were present in the two dairy manures. Conventional dairy manure contained relatively higher contents of soluble inorganic P species and stable metal phytate species. In contrast, organic dairy manure contained more Ca and Mg species of P. These results indicate that P transformation rates and quantities should be expected to differ between organic and conventional dairy manures.

Increased understanding is needed on the interconversion among P species when manure and fertilizer are added to soils. To assess changes in P species affected by manure and fertilizer addition, a sandy loam (no established soil series designation; coarseloamy, mixed, frigid, Typic Haplorthod) and a Lamoine silt loam (fine, illitic, nonacid, frigid Aeric Epiaquept) with no P added, with fertilizer P, and with dairy manures were incubated at 22 °C for up to 108 days. Sequential fractionation with H2O, 0.5 M NaHCO3, and 0.1 M NaOH and phosphatase hydrolysis were used to monitor changes in inorganic P and enzymatically hydrolyzable and nonhydrolyzable organic P during the incubation period. Similar patterns of P dynamics were observed in the two soils. Added inorganic P from either chemical fertilizer or animal manure amendments was found mainly in the NaHCO3 and NaOH fractions. Changes in H2O, NaHCO3, and NaOH-extractable P were similar for P fertilizer–amended soils and unamended soils, indicating that soil properties played a major role in controlling P dynamics. In the H2O fraction, inorganic P attained a low and stable level after an initial rapid decrease. Concentrations of P species in other fractions fluctuated during the incubation period. Furthermore, the fluctuations were observed in complementary patterns between inorganic P in the NaHCO3 and NaOH fractions as well as between labile P (inorganic and hydrolyzable organic) and nonhydrolyzable organic P in the NaOH fraction. These complementary fluctuations implied an interchange of P species during incubation. This interchange could be an important mechanism for maintaining balance between labile and immobile P in soils. Further detailed examination of the patterns of interchange among P fractions in soils may provide more accurate prediction of soil P bioavailability, thus improving soil P management.

A study was made of Massospora levispora and its host, the northern cicada Okanagana rimosa, between 1962 and 1970. The northern cicada O. rimosa is morphologically and ecologically distinct from Okanagana canadensis. Although O. rimosa generally has 5 instars, it occasionally produces a supernumerary instar. The 1st and 2nd stadia each require 1 yr for development, the 3rd and 4th, 2 yr each and the 5th, 3 yr, making a total generation time of 9 years. This species is associated with a blueberry sweet-fern habitat and produces broods whereby usually the cicada is present only every 2 years. Other parasites, predators and pathogens were also investigated. The only parasitoid occuring in this cicada was a previously undescribed sarcophagid, Colcondamyia auditrix. This fly locates its host by the sound produced by the ♂ cicada. Birds and spiders constituted the most important predators. Pathogens found in the cicada nymphs were the fungus Paecilomyces farinosus and a bacterium identified as Corynebacterium okanaganae. The Massospora pathogen occurs only in the above ground population, i.e., adults. Cicadas become infected just prior to emergence by resting spores which then produce conidia; initial infection usually results in production of conidia. Adults cicadas infected by the conidia in turn normally produce only resting spores.

Abstract During the 20th century, American agriculture underwent dramatic changes. At the beginning, farms were more diverse, dependent on animal traction, on-farm inputs and income and, after initial land grants, nearly independent of government policy. However, external issues, such as government policies, mechanization, fossil fuel costs, increased consolidation and vertical integration of markets and increased societal awareness of the environment and concern with farming practices, have substantially altered the structure of agriculture. These external issues are significant drivers of agriculture and we grouped them into social/political, economic, environmental and technological drivers. Previous papers have examined specific effects of these drivers. Our objective is to examine how these drivers interact and influence today's agricultural systems. We developed four categories: (1) Commodity Crop Production, (2) Supply Chain Livestock Production, (3) Organic Production and (4) Extensive Livestock Production, to describe major current agricultural systems. These categories were developed as major and contrasting systems but do not represent all of American agriculture. Although it is not possible to predict the future, interactions among the various drivers will affect these systems differently. By examining multiple scenarios, we conclude the highly specialized systems (Nos. 1 and 2) are highly vulnerable to future changes, and that developing adaptive capacity is critical for dealing with new uncertainty. Sustainable agricultural systems will need balance among various domains to be able to adapt and survive. We suggest that the concept of dynamic-integrated agricultural systems may be the best way to meet this goal because of its ability to consider multiple goals and flexible producer decision-making.

Improved predictive relationships between compost maturity and nitrogen (N) availability are needed. A total of 13 compost samples were collected from a single windrow over a 91 d period. Compost stability and maturity were assessed using both standard chemical analyses (total C and N, mineral N, total volatile solids) and other methods (CO2 evolution, commercial maturity kits, and neutral detergent fiber, and lignin). Compost N and carbon (C) were evaluated during a 130 d aerobic incubation in a sandy loam soil after each compost was applied at 200 mg total kg−1 soil. The effect of compost maturity on plant growth was evaluated by growing two ryegrass (Lolium perenne L.) crops and one barley (Hordeum vulgare L.) crop in succession in compost-amended soil under greenhouse conditions. Potential phytotoxicity from compost was assessed by growing tomato (Lypersicum esculentum L.) seedlings in compost-amended soil. Regression and correlation analyses were used to evaluate the relationship between compost maturity parameters, the rate and extent of net N and C mineralization, plant yield and N uptake, and phytotoxicity. Commonly used maturity parameters like total C, total N, and C:N ratio were poorly correlated with the rate and extent of mineralization, and with plant growth parameters. The N mineralization rate during the first 48 d of aerobic incubation was strongly correlated (r= −0.82 to −0.86) to compost fiber and lignin concentration, and to the Maturity Index (r=0.85). Trends in C mineralization were similar. There were few differences in C mineralization between composts after 48 d of aerobic incubation in soil. Ryegrass harvested 35 and 70 d after compost application was not strongly affected by compost maturity, and relatively immature composts were phytotoxic to tomato seedlings. Methods of characterizing compost maturity and stability that more realistically reflect the composting process are better predictors of N release and potential plant inhibition after incorporation into soil.

Abstract Mechanisms controlling the mineralization and stabilization of organic C and N in soils have been proposed to differ from those for organic P. This study was designed to analyze the climatic and topographic controls on steady‐state levels of soil C, N, and P under relatively undisturbed management. Soil catenas were examined in three climatic zones characterized by mean annual precipitation (MAP) of 395, 444, and 514 mm and mean annual temperature (MAT) of 10.8, 10.7, and 11.5 °C, respectively. Soils of the Argid and Ustoll suborders were studied. Increase in MAP from 395 to 444 mm was associated with increases in organic C and total N of 46 and 24%, respectively. Increasing MAP from 444 to 514 mm with a 0.8 °C increase in MAT did not change organic C and total N; however, levels of organic P increased from 0.144 to 0.167 kg m −3 . Organic‐C concentrations were highest in the surface horizons and declined with depth, but relatively high concentrations of organic P were found in the subsoils studied. The depth of this organic‐P‐accumulation zone varied in patterns indicative of climatic and topographic controls on the leaching process. Both the total contents and vertical distributions of organic C and P, therefore, suggest that stoichiometic relationships between C and P should not be assumed, as both climate and topography may influence soil C and P levels to different extents and through different processes.