Agricultural & Environmental Letters最新文献

Robusta (Coffea canephora Pierre ex Froehner) is a vital cash crop for smallholder farmers in the Ecuadorian Amazon. However, fertility recommendations for robusta production are highly variable across contexts, necessitating regionally tailored recommendations to better diagnose yield-limiting nutrients. Across a gradient of input intensities and agroforestry reflective of local practices, we employed the least absolute shrinkage and selection operator (LASSO) regression to identify which soil fertility measures and leaf nutrients best explained robusta yields across replicated management system treatments in the Ecuadorian Amazon. Leaf nutrients, particularly calcium and magnesium, were stronger and more parsimonious predictors of yields than soil inorganic nitrogen and Mehlich-3 extractable phosphorus and potassium. Although the LASSO model provided reasonable yield estimates (R² = 0.74; root mean square error = 0.23 kg tree⁻¹), model underestimation of yields >1.0 kg tree⁻¹ suggests that other factor(s) not captured by soil and foliar nutrient measures may limit cherry production in higher-yielding systems.

Agronomic use of specialty products known as biostimulants to improve crop productivity is growing. Traditionally, biostimulants are defined as any substance or microorganism applied to plants to enhance nutrient use efficiency, tolerance to abiotic stress, and crop yield and/or quality. However, grouping non-living products with living microbial inoculants poses regulatory guideline challenges. Moreover, peer-reviewed literature and regulatory legislation utilize “biostimulants” while industry and farmers have recently adopted the term “biologicals,” confusing discussions related to product regulation and policy. To better understand the challenges associated with this input sector, we have focused on four critical aspects: (1) the current regulatory status, (2) terminology disparity of biostimulants and biologicals, (3) key attributes that distinguish microorganisms from non-living biostimulants, and (4) mechanism of action differences between plant growth-promoting microorganisms and plant growth regulators. Therefore, we propose that living beneficial microorganisms and non-living biostimulants be separated with distinct regulatory requirements.

Management of phosphorus (P) inputs to agroecosystems is often evaluated by phosphorus use efficiency (PUE), but different calculation approaches may yield discrepancies in estimated PUE values. We evaluated PUE (i) indirectly calculated by difference in crop P uptake between a P-fertilized versus a P-unfertilized control (PUE_diff) and (ii) directly measured by tracing radioisotopically labeled fertilizer P (PUE_isotope). Using two ammonium phosphate fertilizers of high (monoammonium phosphate [MAP]) and low (struvite) water solubility in three soils with non-limiting extractable soil P concentrations (Mehlich-3 P > 25 mg kg⁻¹), we find dissimilar PUE_isotope versus PUE_diff. PUE_diff often yielded negative values (77% of observations), whereas PUE_isotope was (i) positive and (ii) higher (two- to fourfold) for MAP than struvite, and (iii) unassociated with soil Mehlich-3 P concentrations. Thus, PUE_diff appears to underestimate PUE and miss differences in PUE among fertilizerss. Our results raise the need to reconsider calculation of PUE and to address practical challenges to in situ measurement of PUE_isotope.

Knowledge Graphs organize and connect disparate data for integrating information in a user-friendly interface for recommendations and applications. This analytical tool for supporting data interrogation has not been widely applied in agronomy. This article focuses on Knowledge Graph applicability and specifically the utility of the recently released Esri ArcGIS Knowledge platform for identifying system resilience using a community-driven database (Forage Data Hub; 52,997 entries from 108 unique locations over 51 years) comprising legacy datasets encompassing multiple temporal and spatial scales. Overall, perennial systems had greater drought risk resilience estimates (DRRE) than annuals, with alfalfa (Medicago sativa) having a “very high” DRRE across ecoregions. Knowledge Graphs provided information on how geography and agronomic systems interact to impact resilience. Results can be used to design agricultural systems within specific geographic locations with greater resilience and stability in the face of a changing climate per geographic region.

Field plot experiments were conducted over 3 years at two farm sites in Vermont to evaluate the effects of mechanical subsoiling and three pasture cropping mixes on soil compaction across rotationally grazed pasturelands with contrasting management histories in Vermont. Penetration resistance was measured across the 0–45.7 cm profile using both profile-level and depth-stratified analyses. Among the biological treatments, the sudangrass-based mix achieved the greatest compaction alleviation, particularly at the site with higher initial severity. At the northern site (Health Hero [HH] Farm), this mix produced significantly lower median penetration resistance (1.59 MPa) and a narrower interquartile range (0.93 MPa) than other treatments, indicating more uniform soil improvement. At the southern site (Philo Ridge [PR] Farm), keyline plowing resulted in the lowest median resistance (1.41 MPa) but showed greater variability across replicates. Depth-wise trends revealed that biological mixes, particularly the sudangrass-based mix, provided consistent alleviation across soil layers. These findings highlight the value of biologically tailored strategies not only for reducing compaction but also for achieving spatially uniform soil structure recovery. Tailoring species composition to compaction depth offers a practical and lower disturbance alternative to mechanical tillage for improving pasture systems.

The socioeconomic value of content presented at the ASA-CSSA-SSSA (where ASA-CSSA-SSSA is American Society of Agronomy–Crop Science Society of America–Soil Science Society of America) Annual Meetings from 2014 to 2023 is estimated at $64.2 billion and is presented in this commentary as a thought exercise, highlighting the potential scale of research dissemination in scientific meetings. Scientific meetings are instrumental for propelling the quality and advancement of research via fostering timely feedback, knowledge dissemination, fresh perspectives, stimulation for networking and new collaborations, preparing scientists for public engagement, and addressing contemporary challenges of cultural accessibility and opportunity. Additionally, the broader impacts include near-term benefits to agricultural and environmental scientists that can transform careers and perspectives on the world, especially for students and early career members. The benefits from these impacts on scientists are then anticipated to propagate into broader and longer term positive impacts on humanity worldwide. In this commentary, we offer the above as a provocation to spark peer discussion on evaluating scientific meetings’ contributions, alongside a working list of broader impacts to inspire philosophical and methodological innovations for quantifying their value.

Long-term experiments (LTEs) offer unique insights into the effects of agricultural practices on soil organic carbon (SOC). However, early LTEs commonly lack treatment randomization, replication, and initial measurements of SOC. This creates a potential problem of unmeasured confounding. We address this problem using the Morrow Plots (established 1876) as a case study. We start with a standard mixed effects model of SOC and add (i) a spatial kriging component and (ii) SOC measurements in the sod perimeter of the experiment as an additional treatment level. We find that much of the observed SOC variation between treatments after 145 years is not due to treatments but other factors (e.g. initial SOC), attenuating treatment effects by about 50%. Our study demonstrates that creative measurement and innovative modeling can mitigate some deficiencies in early LTEs. However, our improved estimates still have limited precision, suggesting the importance of careful design and measurement in the first place.