Agricultural & Environmental Letters最新文献

The editorial board of Agricultural & Environmental Letters is pleased to announce the recipients of the 2023 Editor's Citation for Excellence. These awards recognize the outstanding professional commitment and dedication of volunteer reviewers and editors who, through their excellent insights and comments, have helped maintain the high standard and quality of papers published in the journal. Recipients were nominated based on their thorough, competent, and timely reviews or editing of manuscripts.

In the last two decades, permanganate has been used to define what is assumed to be a labile or “active” soil carbon (C) pool, commonly referred to as “permanganate-oxidizable carbon” (POXC). However, uncertainties in the reduction reaction (Mn⁷⁺ → Mn⁴⁺/Mn²⁺) and even greater uncertainties in the oxidation reaction (C^? → C^?) as well as the reaction of non-C reductants in the soil sample preclude the calculation of milligram C per kilogram of soil oxidized. Combined variation in the reduction–oxidation reactions can entail up to fivefold variation in how much soil organic C is oxidized per unit permanganate reduced. Without determining final reduction state of Mn and the initial and final oxidation states of C, the amount of C oxidized cannot be calculated. Unless a concrete understanding of the reduction and oxidation half-reactions is achieved, an alternative expression of permanganate reactivity of a soil sample (i.e., not mg C kg⁻¹ soil) is needed.

Cover crops are promoted by agronomists and governments due to their on-farm and off-farm benefits. Incentive programs were created because high planting costs have hindered cover crop adoption in the United States. Crop insurance discount programs are novel incentives that subsidize farmers’ crop insurance premiums by $5 per acre ($12.36 ha⁻¹) on cover cropped land. While this payment is smaller than those typically offered through the Natural Resources Conservation Service and state-level cost-share programs, crop insurance discount programs have the potential to reach a significant proportion of farmers who purchase crop insurance. This paper uses data from a survey of Iowa farmers to quantify whether participation in the Iowa Crop Insurance Discount Program (ICIDP) affects the area planted to cover crops. I find that 11% of the ICIDP area would not have been planted to cover crops in the absence of the program, which is similar to other programs after considering the lower payment rate.

In April 2022, the Environmental Protection Agency (EPA) introduced a workplan for pesticide registration and reregistration to meet obligations under the Endangered Species Act (ESA), which included a menu of suggested mitigation measures to reduce potential for exposure of nontarget species to runoff, spray drift, and erosion. If adopted on registered product labels, it enables a prospective registrant to meet more stringent ESA criteria for registration, even during non-ESA-issued interim decisions. This paper identifies and evaluates complexities posed by the mitigation menu approach that could undermine good intentions underlying this new process and uses existing economic considerations to analyze positive and negative externalities. Several points of complexity demonstrate how the mitigation menu approach would benefit from further regulatory development or refinement. Changes should be informed by fundamental questions about the dynamics between landowners and land managers and, crucially, different motivations decision-makers face in adopting voluntary versus regulatory mitigations.

Understanding where, when, and why agroecosystems are changing requires quality information about ecosystems that span land tenure, ecological processes, and spatial scales. Over the past two decades, land management agencies and research groups have adopted a suite of standardized methods for monitoring rangelands, which have been implemented at over 85,000 monitoring locations globally. However, the ability to use these data to understand agroecosystem dynamics and change across scales and across land ownership has been limited because, until now, these data have not been available in a harmonized, accessible format for analyses, modeling, and decision-support tools. We present the Landscape Data Commons, a cyberinfrastructure platform that harmonizes and aggregates standardized agroecosystem data, enables linkages to models, and facilitates analysis and interpretation of data within decision-support tools. The Landscape Data Commons provides a community platform for users to contribute data and develop next-generation tools to support agroecosystem management through the 21st century.

This study evaluates cover crop (CC) effects on microbial community structure in a winter wheat–sorghum–fallow rotation with pea, oat, and canola; mixtures of pea and oat; pea and canola; pea, oat, and canola; and six species mixture (SSM) of pea, oat, canola, hairy vetch, forage radish, and barley as CCs, and fallow as treatments. Soil microbial community structure was analyzed at CC termination (phase I), 36 days (phase II), and a year (phase III) after termination using an ester-linked fatty acid methyl ester analysis. Total microbial biomass (TMB) under oats was significantly greater than under canola (by 47%) in phase I (p ≤ 0.05). The TMB was >48% under pea, pea + canola, and SSM, and arbuscular mycorrhizal fungi was 70%–93% more under pea, canola, and their mixtures than fallow in phase II. While microbial abundance varied with CCs at and after 36 days post-termination, these effects did not persist for a year. Long fallow period after cropping or cover cropping appears detrimental to microbial community proliferation.

Soil respiration is one of the main soil health indicators and is influenced by several factors in agricultural fields. Identifying key factors that control soil respiration is desirable for informed soil management decisions and for promoting and scaling up soil health. This study aimed to (i) quantify the relationships between potential soil respiration and selected soil properties, crops, and slope positions, and (ii) identify key factors controlling these relationships using a neural network model. Ninety soil samples from 0- to 5- and 5- to 20-cm soil depth were collected from footslope, backslope, and summit in three fields planted with soybean (Glycine max L. Merr.), alfalfa (Medicago sativa L.), and corn (Zea mays L.). The model provided great accuracy (coefficient of determination: 0.96; root-mean square error: 7.8; and mean absolute deviation: 3.8) and explained nearly 96% of variations in soil respiration across soil depth, crop, and slope positions. Soil depth, ammoniacal nitrogen (NH₄-N), crop types, slope position, and silt content were identified as the top five factors influencing potential soil respiration at the field level. Potential soil respiration was more sensitive to potassium, phosphorus, pH, cation exchange capacity, and mean weight diameter and less sensitive to NH₄-N, nitrate nitrogen, soil organic matter, and clay content. It increased with pH, electrical conductivity, mean weight diameter, potential nitrogen mineralization, and potassium, and it decreased with increasing silt content. Soil from 0 to 5 cm under soybean or at the summit slope position exhibited a higher respiration. Using a small dataset, this pilot study accurately predicted potential soil respiration in agricultural fields and identified key drivers controlling it. The results from this study highlight the complexity of using potential soil respiration as a standalone test for evaluating soil health. This does not diminish the usefulness of potential soil respiration as a soil health indicator to support agricultural management decisions and as a reference in future soil health studies. However, it emphasizes the importance of considering multiple factors when interpreting the significance of soil biological indicators for soil health assessments.

Ammonium phosphate fertilizers are a common phosphorus (P) source for crops, namely monoammonium phosphate, diammonium phosphate, and ammonium polyphosphate. Despite containing appreciable nitrogen (N), ammonium phosphate fertilizers are generally considered P fertilizers. However, the approximately 8.5 million Mg N co-applied with P annually as ammonium phosphate fertilizers represents 8% of global N fertilizer input flux to agroecosystems. Despite this, a systematic review of the literature revealed only one direct assessment of N losses from ammonium phosphate fertilizers. An additional five studies reported NO₃-N leaching and N₂O-N emissions from soils fertilized with ammonium phosphates, but inadvertently as observations from failed or control treatments that are confounded (e.g., not accounting for non-fertilizer contributions to N losses). The magnitude and fate of N co-applied with P in ammonium phosphate fertilizers is a blind spot in agroecosystem N budgets and environmental footprints that necessitates quantification.

Although communicating research is a key part of public science, current graduate curricula in the agricultural sciences usually have a narrow focus on communication appropriate for presenting to scientific and academic audiences, such as in the form of the dreaded “seminar.” Yet the importance and impact of agriculture extends well beyond research communities, and communicating with other potential audiences is essential for realizing the full impact of research. Because public speaking is among the greatest fears for many people, it is critical to provide students with the tools needed to communicate effectively with diverse audiences, particularly as only a fraction of them will go on to give regular research seminars once they enter the professional world. Better communication can lead to more constructive engagement with the public as well as with policy-makers, toward improved understanding of the science they are funding and from which they are benefiting. Purposeful instruction in public speaking should help alleviate the common anxieties that student presenters often experience. Here, we summarize general communication strategies that can be incorporated into any graduate agricultural science course to help address this need.