About the Journal

Agronomy Journal is the flagship journal of ASA. Articles convey original research in agriculture, natural resources, soil science, crop science, agroclimatology, agronomic modeling, production agriculture, and instrumentation.

Featured Article

Journal Issue Cover 113/5
On the Special Section, International Turfgrass Research Conference 2022

This special issue showcases research to be presented at the 2022 International Turfgrass Research Conference to be held in Copenhagen, Denmark. Read the introduction by Dr. Trygve Aamlid here.

Browse Articles

Cover Image, Volume 113, Issue 5

  •  20 October 2021

Abstract

On the cover: Water conservation and nutrient fate in the urban landscape are increasingly important issues as urbanization and population growth continue to strain existing natural resources. Landscape irrigation and surface hydrology research has been conducted at the Urban Landscape Runoff Facility at Texas A&M University for the past decade. The facility is equipped with 24 sloped plots capable of measuring runoff volume and capturing samples for contaminant analysis. Recent studies have contributed information on rainfall-runoff processes, irrigation scheduling, and nutrient fate for landscapes featuring turfgrasses, non-turfgrass plantings, and hardscapes. See the article, “Effective rainfall estimates for St. Augustinegrass lawns under varying irrigation programs”, by Fontanier et al. in this issue of Agronomy Journal. Photo Credit: Richard White, Texas A&M University.

Interactions of cultivar, sowing date, and growing environment differentially alter wheat phenology under climate warming

  •  8 October 2021

Core Ideas

  • Wheat phenology was simulated under various farming and warming conditions.
  • Simulations considered various cultivars, sowing dates, and growing environments.
  • The advancement of wheat phenology varied substantially depending on these interactions.
  • Delayed sowing and changing to winter from spring-type cultivars are effective adaptations.
  • Adaptations should be carefully planned considering these interactions.

Open access

Planting date and maturity group impact on soybean seed quality in the southeastern United States

  •  8 October 2021

Core Ideas

  • Early-maturing varieties had a lower protein content than later-maturing varieties.
  • Protein content was consistent across planting date for later-maturing varieties.
  • Seed damage was greatest when planting before late April with early MGs (2-4).
  • Purple seed stain was lower in MGs 5-7 compared with the earlier MGs across all planting dates.

Assessment of fodder resources in Ethiopia: Biomass production and nutritional value

  •  7 October 2021

Core Ideas

  • Production of crop residues, aftermath grazing, and forest land increased over time.
  • The crude protein of natural pasture was higher in the highland than midland and lowland.
  • Altitude had different effects on nutritive value of cultivated forages.
  • The crude protein and digestibility of indigenous browse species were higher during the wet season.
  • Crop residues and natural pastures have low nutritional quality.

The cotton GhMYB4 gene enhances salt and drought tolerance in transgenic Arabidopsis

  •  7 October 2021

Core Ideas

  • The cotton GhMYB4 gene improved flavonoids accumulation.
  • GhMYB4 enhanced salt and drought tolerance in transgenic Arabidopsis plants.
  • Overexpression of GhMYB4 increased the expression of genes involved in flavonoid biosynthesis
  • GhMYB4 overexpression up-regulated the expression of genes related to abiotic stresses.

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Livestock feed resources in the West African Sahel

Core Ideas

  • Productivity of livestock in West Africa Sahel is constrained by limited supply of quality feed
  • Feed quality is low, and availability varies seasonally, reducing livestock productivity
  • Rangeland, crop residues and agro-industrial by-products are important feed resources in Sahel
  • Improving nutritive quality of crop residues, fodder preservation, and better feed marketing are needed
  • Identifying available feed resources is necessary for designing interventions for improvement

One‐time N fertilization reduces greenhouse emissions and N leaching while maintaining high yields in a rape‐rice rotation system

Core Ideas

  • The integrated effects of CRU on rice-rapeseed (R-R) rotation were quantified.
  • The rice-growing season contributed over 95% and 50% of the annual CH4 and N2O emissions.
  • NO3 was the main leaching loss in rape season, while for rice season NO3 and NH4+ were equal.
  • CRU reduced mean annual TGHGs and N leaching by 10.7% and 12.1%, without sacrificing crop yield.
  • Labor cost savings could offset the high cost of CRU.

Spatial and temporal variability of soil organic carbon on a corn‐soybean watershed with 23 years of agroforestry

Core Ideas

  •  Sequestration of carbon in soils under grass and agroforestry buffers was evaluated after 23-years of implementation.
  •  Agroforestry and grass buffers increased the soil organic carbon (SOC) among watersheds and treatments.
  •  This study indicates the importance of agroforestry buffers on carbon sequestration, leading to healthier soils and mitigate climate change.
  •  Soil depth and landscape positions are important factors affecting C distribution in soils.

Cotton row spacing and Unmanned Aerial Vehicle (UAV) sensors

Core Ideas

  • Evaluation of the accuracy of UAV sensors to predict lint yield validates HTP technology.
  • Demonstrated the improvement of cotton yield predictions with UAV sensors in skip row patterns.
  • GxE with row spacing was minimal, so UAVs can be used to predict cotton yield

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Hydrometer Method Improved for Making Particle Size Analyses of Soils1

Synopsis

The time required for dispersing soils for the hydrometer method of making particle size analyses was reduced from 25 minutes to only 2 minutes. The procedure consists of soaking the soils in a 5% Calgon solution for 15 to 20 hours and then dispersing them with a soil mixer running at a speed of about 16,000 r.p.m., for 2 minutes.

AquaCrop—The FAO Crop Model to Simulate Yield Response to Water: I. Concepts and Underlying Principles

Abstract

This article introduces the FAO crop model AquaCrop. It simulates attainable yields of major herbaceous crops as a function of water consumption under rainfed, supplemental, deficit, and full irrigation conditions. The growth engine of AquaCrop is water-driven, in that transpiration is calculated first and translated into biomass using a conservative, crop-specific parameter: the biomass water productivity, normalized for atmospheric evaporative demand and air CO2 concentration. The normalization is to make AquaCrop applicable to diverse locations and seasons. Simulations are performed on thermal time, but can be on calendar time, in daily time-steps. The model uses canopy ground cover instead of leaf area index (LAI) as the basis to calculate transpiration and to separate out soil evaporation from transpiration. Crop yield is calculated as the product of biomass and harvest index (HI). At the start of yield formation period, HI increases linearly with time after a lag phase, until near physiological maturity. Other than for the yield, there is no biomass partitioning into the various organs. Crop responses to water deficits are simulated with four modifiers that are functions of fractional available soil water modulated by evaporative demand, based on the differential sensitivity to water stress of four key plant processes: canopy expansion, stomatal control of transpiration, canopy senescence, and HI. The HI can be modified negatively or positively, depending on stress level, timing, and canopy duration. AquaCrop uses a relatively small number of parameters (explicit and mostly intuitive) and attempts to balance simplicity, accuracy, and robustness. The model is aimed mainly at practitioner-type end-users such as those working for extension services, consulting engineers, governmental agencies, nongovernmental organizations, and various kinds of farmers associations. It is also designed to fit the need of economists and policy specialists who use simple models for planning and scenario analysis.

Climate Impacts on Agriculture: Implications for Crop Production

Abstract

Changes in temperature, CO2, and precipitation under the scenarios of climate change for the next 30 yr present a challenge to crop production. This review focuses on the impact of temperature, CO2, and ozone on agronomic crops and the implications for crop production. Understanding these implications for agricultural crops is critical for developing cropping systems resilient to stresses induced by climate change. There is variation among crops in their response to CO2, temperature, and precipitation changes and, with the regional differences in predicted climate, a situation is created in which the responses will be further complicated. For example, the temperature effects on soybean [Glycine max (L.) Merr.] could potentially cause yield reductions of 2.4% in the South but an increase of 1.7% in the Midwest. The frequency of years when temperatures exceed thresholds for damage during critical growth stages is likely to increase for some crops and regions. The increase in CO2 contributes significantly to enhanced plant growth and improved water use efficiency (WUE); however, there may be a downscaling of these positive impacts due to higher temperatures plants will experience during their growth cycle. A challenge is to understand the interactions of the changing climatic parameters because of the interactions among temperature, CO2, and precipitation on plant growth and development and also on the biotic stresses of weeds, insects, and diseases. Agronomists will have to consider the variations in temperature and precipitation as part of the production system if they are to ensure the food security required by an ever increasing population.

Improving Nitrogen Use Efficiency for Cereal Production

Abstract

Worldwide, nitrogen use efficiency (NUE) for cereal production (wheat, Triticum aestivum L.; corn, Zea mays L.; rice, Oryza sativa L. and O. glaberrima Steud.; barley, Hordeum vulgare L.; sorghum, Sorghum bicolor (L.) Moench; millet, Pennisetum glaucum (L.) R. Br.; oat, Avena sativa L.; and rye, Secale cereale L.) is approximately 33%. The unaccounted 67% represents a $15.9 billion annual loss of N fertilizer (assuming fertilizer-soil equilibrium). Loss of fertilizer N results from gaseous plant emission, soil denitrification, surface runoff, volatilization, and leaching. Increased cereal NUE is unlikely, unless a systems approach is implemented that uses varieties with high harvest index, incorporated NH4-N fertilizer, application of prescribed rates consistent with in-field variability using sensor-based systems within production fields, low N rates applied at flowering, and forage production systems. Furthermore, increased cereal NUE must accompany increased yields needed to feed a growing world population that has yet to benefit from the promise of N2-fixing cereal crops. The Consultative Group on International Agricultural Research (CGIAR) linked with advanced research programs at universities and research institutes is uniquely positioned to refine fertilizer N use in the world via the extension of improved NUE hybrids and cultivars and management practices in both the developed and developing world.

Analysis and Interpretation of Factors Which Contribute to Efficiency of Nitrogen Utilization1

Abstract

Differences in N response among corn (Zea mays L.) genotypes reflect variation in numerous processes involved in N use efficiency. In order to facilitate the study of such variation, we develop and demonstrate a concept for evaluating the contribution of N uptake and utilization processes to variation in N use efficiency. Eight hybrids were grown in a replicated field experiment at two levels of N fertilizer on a Dothan loamy sand (Typic Plinthic Paleudult). Differences among the hybrids for components of N use efficiency were evaluated from measurements of grain yield, N accumulation in the plant at silking, and N accumulation in the grain and stover at harvest. Significant differences were found among hybrids and between N levels for all traits. Interactions among hybrids and N levels were significant for all traits except grain yield. At low N supply, differences among hybrids for N use efficiency were due largely to variation in utilization of accumulated N, but with high N they were due largely to variation in uptake efficiency. Variation in proportion of N translocated to grain was also important at the low N supply. Variation in N accumulated after silking was not important at either level of N supply. Variation in N remobilization from vegetative tissue to grain was moderately important at the low N supply. Hybrids with similar levels of N use efficiency showed marked differences in component traits which contribute to efficiency.

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