Timing of precision agriculture technology adoption in US cotton production

The timing of technology adoption is influenced by profitability and farmer ability to bear risk. Innovators are typically more risk tolerant than laggards. Understanding the factors influencing early adoption of precision agriculture (PA) technologies by cotton farmers is important for anticipating technology diffusion over time. The factors influencing the timing of grid soil sampling (GSS), yield monitoring (YMR) and remote sensing (RMS) adoption by cotton producers was evaluated using multivariate censored regression. Data for cotton farmers in 12 states were obtained from a survey conducted in 2009. The factors hypothesized to influence the timing of adoption included farm characteristics, operator characteristics, PA information sources, adoption of other PA technologies, and farm location. The results suggest that different factors influenced when cotton farmers adopted GSS, YMR and RMS after these technologies became commercially available. For example, land ownership was associated with the timing of GSS adoption, but not YMR or RMS adoption; farmer age was correlated with the timing of GSS and YMR adoption, but not RMS adoption; and obtaining PA information from consultants affected the timing of GSS and RMS adoption, but not YMR adoption. The only factors correlated with the early adoption of all three technologies were beliefs that PA would improve environmental quality and the adoption of at least one other PA technology. Thus, the potential for improved environmental quality appears to be a strong adoption motivator across PA technologies, as is the earlier adoption of other PA technologies. This research may be useful for farmers, researchers, Extension personnel, machinery manufacturers, PA information providers and agricultural retailers to anticipate the future adoption of new and emerging PA technologies.     

Estimation of critical nutrient range of petiole nitrate for sprinkler-irrigated potatoes

The relationship of yield to concentration of NO₃ in petioles of potatoes (Solanum tuberosum L.) was studied as part of a comprehensive project on N use efficiency. The objective of this study was to estimate the critical nutrient range (CNR) of petiole NO₃ for Russet Burbank potatoes treated with N supplements during the season. Treatments totaled 224, 336, and 560 kg N ha^-1 for the season as NH₄NO₃ on this low N soil with one-third to one-half of the N applied at planting and the rest as periodical supplements during the season. Average yield of potatoes (74 Mt ha^-1) was highest with 336 kg N ha^-1. From this it was assumed that 224 N was optimum. Petiole NO₃ decreased through the season with linear regressions of petiole NO₃ versus time for each of three N rates accounting for variation in petiole NO₃. It was concluded that at the start of the season, the estimated CNR for petiole NO₃-N of potatoes was within the range from 9 to 13 g kg^-1. Numerically, CNR values decrease with time as the season progresses. It is concluded that until more precise calibrations are made available, the CNR approach with petiole NO₃ will be more helpful in cross checking the nutritional status of potatoes fertilized periodically with N supplements than in serving as a primary fertilizer guide.     

Soil texture prediction through stratification of a regional soil spectral library

Knowing the spatial distribution of soil texture,which is a physical property,is essential to support agricultural and environmental decision making.Soil texture can be estimated using visible,near infrared,and shortwave infrared(Vis-NIR-SWIR)spectroscopy.However,the performance of spectroscopic models is variable because of soil heterogeneity.Currently,few studies address the effects of soil sample variability on the performance of the models,especially for larger spectral libraries that include soils that are more heterogeneous.Therefore,the objectives of this study were to:i)apply Vis-based color parameters on the stratification of a regional soil spectral library;ii)evaluate the performance of the predictive models generated from the spectral library stratification;iii)compare the performance of stratified models(SMs)and the model without stratification(WSM),and iv)explain possible changes in prediction accuracy based on the SMs.Thus,a regional soil spectral library with 1535 samples from the State of Santa Catarina,Brazil was used.Soil reflectance data were obtained by Vis-NIR-SWIR spectroscopy in the laboratory using a spectroradiometer covering the 350–2500 nm spectral range.Sand,silt,and clay fractions were determined using the pipette method.Twenty-two components of color parameters were derived from the Vis spectrum using the colorimetric models.A cubist regression algorithm was used to assess the accuracy of the applicability of the initial models(SMs and WSM)and of the validation between the clusters.Fractional order derivatives(FODs)at 0.5,1.5,and 2 intervals were used to explain possible changes in the performance of the SMs.The SMs with higher contents of clay and iron oxides obtained the highest accuracy,and the most important spectral bands were identified,mainly in the 480–550 and 850–900 nm ranges and the 1400,1900,and 2200 nm bands.Therefore,stratification of soil spectral libraries is a good strategy to improve regional assessments of soil resources,reducing prediction errors in the qualitative determination of soil properties.     

生态毒理学工具在评价石油化工厂区土地耕作适宜性中的运用

The demand for simple and rapid bioassays in ecotoxicological evaluations is of paramount importance in order to speed up environmental monitoring programs. In this study we performed bioassays with lettuce seeds and two species of terrestrial isopods （Armadillidium vulgare and Porcellio dilatatus） for the ecotoxicological assessment of a landfarming soil from a petrochemical complex area. The solubilized content of test soil demonstrated a concentration-response type toxic effect on seed germination rate, and a delay on germination, but showed toxic effect on seedlings wet weight only at the highest concentration. Toxic effects were also observed in mortality rate and avoidance behavior of the two woodlice species. These results demonstrated the sensitiveness of the organisms studied, and highlighted the possibility to use these bioassays in environmental monitoring programs in areas contaminated with fossil fuels.     

Efficiency of soil-applied 67Zn-enriched fertiliser across three consecutive crops

A very small amount of applied zinc (Zn) is taken up by crops, resulting in low recovery by plants. Adding elemental sulphur to zinc oxide (ZnO) fertiliser could improve Zn solubilisation and exert a higher residual effect on crops than soluble Zn sources. We produced an isotopically labelled Zn-elemental sulphur fertiliser and evaluated its performance in comparison to traditional Zn sources during sequential crop cultivation. Three ⁶⁷Zn-labelled fertilisers, ZnO, zinc sulphate (ZnSO₄), and ZnO co-granulated with elemental sulphur (ZnOS⁰), were soil applied, and their contributions to the uptake of Zn by three consecutive crops, wheat, ryegrass, and corn, were assessed in a 294-d pot experiment. The contributions of Zn fertilisers followed the order:ZnSO₄ > ZnO=ZnOS⁰. The relative contributions of Zn fertilisers were lower in the first crop than in the subsequent crops. The overall recovery of applied Zn by the three crops was higher for ZnSO₄ than for ZnO and ZnOS⁰, reaching 1.56%, 0.45%, and 0.33% of the applied Zn, respectively. Zinc recovery by plants was very low, regardless of the source of Zn. Adding elemental sulphur to ZnO did not increase its effectiveness up to 294 d after application. Fertiliser contribution was higher for the subsequent crops than for the initial crop, indicating the importance of assessing the residual effects of Zn fertilisers.     

Responses of Common Pot Grown Flower Species To Commercial Plant Growth Media Substituted With Vermicomposts

Waste management is an increasingly important problem in many developed countries and much effort is currently being expended into identifying novel uses for waste products. We consider the effects of substituting proportions of earthworm-digested composted green waste (vermicompost) into commercial peat based growing media on the germination, growth, and productivity of Helianthus annuus, Cosmos bipinnatus and Eschscholzia californica. The percentage germination, time to flowering, seed production, overall heights and biomass were measured for all three species in treatments of commercial peat based growing media where the growth medium was substituted with vermicompost at rates of 0%, 20%, 40%, 60% and 100%. In addition, the total numbers of inflorescences was recorded in multiple flowering species. Results for Helianthus suggest that while vermicompost additions induced small species specific growth responses in germination rate, growth rate, overall height and total biomass, none were statistically significant. For Cosmos there was a significant increase in early plant growth rate and in the final flower numbers at substitution rates of 20% and 40% vermicompost. The total biomass and numbers of flowers produced by Eschscholzia was decreased significantly by substitution of 20% and 40% vermicompost. We conclude that the plant growth enhancement properties of this vermicompost seem more species specific than previously reported. Further, in order to preserve consumer confidence in waste-derived horticulture products, vermicompost marketing strategies should acknowledge these findings.     

Soil microbial biomass and bacterial and fungal community structures responses to long-term fertilization in paddy soils

Purpose

Long-term fertilization can influence soil biological properties and relevant soil ecological processes with implications for sustainable agriculture. This study determined the effects of long-term (>25 years) no fertilizer (CK), chemical fertilizers (NPK) and NPK combined with rice straw residues (NPKS) on soil bacterial and fungal community structures and corresponding changes in soil quality.

Materials and methods

Soil samples were collected from a long-term field site in Wangcheng County established in 1981 in subtropical China between mid summer and early autumn of 2009. Terminal restriction fragment length polymorphism (T-RFLP) and the real-time quantitative polymerase chain reaction (real-time qPCR) of bacterial and fungal community and microbial biomass (MB-C, -N and -P) were analyzed.

Results and discussion

Redundancy analysis of the T-RFLP data indicated that fertilization management modified and selected microbial populations. Of the measured soil physiochemical properties, soil organic carbon was the most dominant factors influencing bacterial and fungal communities. The bacterial and fungal diversity and abundance all showed increasing trends over time (>25 years) coupling with the increasing in SOC, total N, available N, total P, and Olsen P in the fertilized soils. Compared to chemical fertilizer, NPKS resulted in the greater richness and biodiversity of the total microbial community, soil organic C, total N, MB-C, -N and -P. The high biodiversity of microbial populations in NPKS was a clear indication of good soil quality, and also indicated higher substrate use efficiency and better soil nutrient supplementation. Otherwise, unfertilized treatment may have a soil P limitation as indicated by the high soil microbial biomass N: P ratio.

Conclusion

Our results suggest that NPKS could be recommended as a method of increasing the sustainability of paddy soil ecosystems.     

Accidental 5-Fluorouracil Exposure in a Dog

objective: To demonstrate the range of toxicities with 5-Fluorouracil (5-FU).
Case Summary: A one-year-old male castrated Labrador Retriever presented to the University of Minnesota Veterinary Teaching Hospital Emergency Service following accidental ingestion of a 5% 5-Fluorouracil (5-FU) topical antineoplastic cream. The animal presented with status epilepticus and later demonstrated additional clinical signs consistent with 5-FU toxicosis including mucositis and diarrhea, profound but transient leukopenia, and thrombocytopenia.
New Information Provided: The calculated ingested dosage was 46 mg/kg. The dog responded well to intensive therapy, recovering uneventfully.