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Biological indicators are often used to evaluate the effect of management practices on soil health. However, determining which indicators can detect changes in soil health after implementation of conservation practices and how these indicators relate to plant growth in grass seed production systems remains unclear. The goal of this study was to explore the relationships between management practice history, soil health metrics, plant growth, and soil microbial communities in annual ryegrass grown under greenhouse conditions. Soils were collected from 12 annual ryegrass [Lolium multiflorum (L.) Husnot] fields managed under conventional (till/bale) or conservation (no‐till/full straw) management practices, with three silt loams and three silty clay loams collected for each practice. Annual ryegrass was grown for 5 months on each of the 12 soils in a greenhouse. Soils with a history of conservation management improved the majority of the carbon cycling‐related metrics for the silt loam soils. Management practices had no effect on seed yield, however, conservation management significantly improved aboveground biomass in silty clay loam soils. Contrasting management practices resulted in distinct microbial communities, making them sensitive indicators of changes in soil conditions. Soil health and plant metrics were positively associated with the microbial communities in soils under conservation management. Total C and organic matter were positively correlated to plant parameters in silt loams, while few indicators were correlated to plant metrics in silty clay loams. These results highlight the complex interplay between microbial communities, soil health, and plant growth and the importance of considering inherent soil properties like texture. Core Ideas: The relationship between management practices and soil health and yield outcomes were influenced by soil texture.Biological soil health indicators and yield metrics were positively correlated in silt loam soils.Microbial communities were a sensitive indicator of changes in management practices.Microbial communities in no‐till were positively correlated to yield and soil health metrics. [ABSTRACT FROM AUTHOR]

Approximately 37% of US milk production occurs in semiarid regions, providing an opportunity to recycle manure nutrients through a variety of cropping systems. Accurate prediction of nitrogen (N) mineralization is critical to determine manure application suitability in intensive irrigated agriculture as many crops in the region have quality parameters that are sensitive to N. Research was conducted in southcentral Idaho to evaluate N mineralization via a buried bag methodology to develop a predictive N‐mineralization model. The study was arranged in a randomized complete block design with manure application rates of 18, 36, and 52 Mg·ha−1 (dry weight basis) both annually and biennially with synthetic fertilizer and untreated check treatments. The crop rotation included small‐grain and broadleaf crops. In the final year of the study, preplant soil organic carbon, total nitrogen, and NO3–N concentrations were positively linearly correlated with manure application rate. Nearly five times as much N was mineralized annually in the 0‐ to 30‐cm depth as compared to the 30‐ to 60‐cm depth. Increased rates of N mineralization for each kilogram of added N occurred in years when residue from broadleaf crops (slope = 0.17) was applied as compared to years with manure only application (slope = 0.07). Stepwise modeling determined that the most predictive model for seasonal N mineralization (R2 = 0.79) included manure N, residue N, soil organic matter, and electrical conductivity. These results allow preplant N mineralization estimation and will prove critical for managing manure in semiarid regions for agronomic, economic, and environmentally sound crop production. Core Ideas: Tools are needed to estimate nitrogen (N) mineralization from applications of dairy manure in semiarid irrigated soils.N mineralization was affected by manure application rate, timing, and broadleaf residue N.Average manure N mineralization was 27% and 18% of N applied in the first and second years, respectively, following application.The incorporation of broadleaf residue with manure increased N mineralized to 41% of N applied.The best predictors of N mineralization were soil organic matter, soil electrical conductivity, manure N, and broadleaf N residue. [ABSTRACT FROM AUTHOR]

Understanding the S nutritive value of biosolids produced by various processing methods is important for growers who apply biosolids to crop production fields. Our project goals were to determine how processing method and biosolids' properties influence S availability and S fertilizer value. Fourteen biosolids materials were selected for the trial, including those produced with aerobic digestion (n = 2), anaerobic digestion (n = 5), dual digestion (n = 1), composting (n = 2), lagoon storage (n = 2), sawdust blending (n = 1), and alkaline stabilization (n = 1). Biosolids were air‐dried, ground, and added to a Walla Walla silt loam soil at a rate of 100 mg S kg–1 soil. The treated soils were incubated at 25 ℃ and extracted for SO4–S on Days 1, 13, 29, 44, and 83. Mean plant available S was greatest for the alkaline stabilized biosolids (52%), followed by anaerobically digested biosolids (40%), sawdust blended biosolids (37%), lagoon slurry (36%), dual digestion biosolids (31%), aerobically digested biosolids (15%), and composted biosolids (4%). Biosolids pH, organic C/total S, total Ca, total S, and SO4–S concentrations were well correlated to S release rate, plant available S, or both. Sulfur mineralization of organic S compounds is known to be influenced by organic C/total S, whereas Ca and pH effects may be related to gypsum (CaSO4) dissolution and oxidation of hydrogen sulfide compounds. The correlations discussed here may need to be further investigated and verified on additional soil types and under field conditions prior to grower adoption. Core Ideas: Biosolids processing method significantly affected S availability.Biosolids C/S, Ca, and pH were correlated to biosolids S availability.Gypsum dissolution, S mineralization, and S oxidation may be driving S availability. [ABSTRACT FROM AUTHOR]

Central Oregon is an important production region for hybrid carrot (Daucus carota L.) seed. Hybrid carrots are favored by the fresh vegetable market, but often produce lower and less consistent seed yields than traditional open-pollinated varieties. Understanding how hybrid carrots use nutrients to support seed production for hybrid varieties can help growers manage soil fertility for optimal seed yield. The objective of this research was to evaluate seasonal nutrient partitioning and uptake in a modern Nantes-type hybrid carrot grown for seed. Plants from four randomized replicated plots in two commercial fields were destructively sampled throughout the growing season, separated into roots, tops, and umbels; seed samples were collected at harvest. Plant samples were weighed and dried for biomass content and analyzed for N, P, K, S, Ca,Mg, Na, Zn, Fe,Mn, Cu, and B concentration. Mean whole plant nutrient uptake at crop maturity for N, P2O5, K2O, S, Ca, Mg, and Na was 137, 35, 229, 16, 105, 38, and 25 kg ha-1, respectively; Zn, Fe, Mn, Cu, and B uptake was 156, 1,984, 414, 35, and 305 g ha-1, respectively. Our findings highlighted the critical need for Cu in initial crop establishment, for N, K, Zn, and Fe in crown development, and for P and Zn in seed development, based on nutrient uptake proportion relative to the other nutrients taken up during that period. This information is available as a resource to agronomists, crop advisors, and growers who are interested in optimizing nutrient management practices for hybrid carrot seed production. [ABSTRACT FROM AUTHOR]

Advanced soil tests can improve the estimation of plant available nutrients to better match fertilizer additions with plant needs and, in some cases, provide a measure of soil health. In the present study, 334 samples from four separate studieswere evaluated using the Soil Health Tool (SHT) vs. the standard regional (University of Idaho [UI] Guidelines) method for determining fertilizer application, assuming a crop of spring irrigated wheat. Recommended N applications using the SHT were ~138 kg ha-1 greater than the UI recommendations. Nitrogen mineralization predicted using the SHT (47 kg ha-1) was similar to the N mineralization value used in the regional methodology (50 kg ha-1). The P fertilizer recommendations were similar between the two methodologies with the SHT recommending, on average 4.7 kg ha-1 less P than the regional method. The lower P recommendation are likely due to a lack of accounting for the effects of high calcium carbonate levels on the P availability from fertilizers in this region. The soil health score (SHS) was correlated with measures of soil C but was not positively correlated to crop yield. In some instances, increasing SHS were correlated with decreases in crop quality as the addition of manure increased soil C but also created issues such as high salt contents and release of late season N. With modification to more accurately represent irrigation conditions and including sampling to greater soil depths, the SHT may be tailored to better estimate soil nutrient status and provide better fertilizer recommendations for the region. [ABSTRACT FROM AUTHOR]