Corn nitrogen rate recommendation tools’ performance across eight US midwest corn belt states

Determining which corn (Zea mays L.) N fertilizer rate recommendation tools best predict crop N need would be valuable for maximizing profits and minimizing environmental consequences. Simultaneous comparisons of multiple tools across various environmental conditions have been limited. The objectives of this research were to evaluate the performance of publicly‐available N fertilizer recommendation tools across diverse soil and weather conditions for: (i) prescribing N rates for planting and split‐fertilizer applications, and (ii) economic and environmental effects. Corn N‐response trials using standardized methods were conducted at 49 sites, spanning eight US Midwest states and three growing seasons. Nitrogen applications included eight rates in 45 kg N ha−1 increments all at‐planting and matching rates with 45 kg N ha−1 at‐planting plus at the V9 development stage. Tool performances were compared to the economically optimal N rate (EONR). Over this large geographic region, only 10 of 31 recommendation tools (mainly soil nitrate tests) produced N rate recommendations that weakly correlated to EONR (P ≤ .10; r2 ≤ .20). With other metrics of performance, the Maximum Return to N (MRTN) soil nitrate tests, and canopy reflectance sensing came close to matching EONR. Economically, all tools but the Maize‐N crop growth model had similar returns compared to EONR. Environmentally, yield goal based tools resulted in the highest environmental costs. Results show that no tool was universally reliable over this study\u27s diverse growing environments, suggesting that additional tool development is needed to better represent N inputs and crop utilization at a larger regional level

Propriedades químicas de uma Terra Roxa Estruturada influenciadas pela cobertura vegetal de inverno e pela adubação orgânica e mineral

O presente trabalho teve por objetivo avaliar a influência da cobertura vegetal de inverno, constituída de uma associação de aveia preta (Avena strigosa Schreb) com nabo forrageiro (Raphanus sativus L.), da adubação orgânica com esterco de aves e da adubação mineral sobre propriedades químicas de uma Terra Roxa Estruturada do estado de Santa Catarina. As análises foram realizadas em amostras de solo coletadas em agosto de 1994 e janeiro de 1995, nas profundidades de 0-10, 10-20 e 20-30 cm, em um experimento iniciado em 1990. Observou-se que a cobertura vegetal de inverno mostrou-se eficiente na manutenção de nutrientes, especialmente o potássio, e dos níveis de carbono orgânico, dentro dos limites da camada arável. O uso de adubo orgânico proporcionou acúmulo de nutrientes no solo, enquanto os adubos organomineral e mineral mostraram tendência de redução, principalmente dos níveis de potássio do solo

Alkaline stabilization of manure slurry inactivates porcine epidemic diarrhea virus

Hydrated lime manure treatment was evaluated to determine porcine epidemic diarrhea virus (PEDV) susceptibility to alkaline stabilization. At pH 10, PEDV decreased (quantitative polymerase chain reaction) and lost infectivity (swine bioassay). Although ammonium decreased above pH 9 (up to 25%), alkaline stabilization managed to control potential infection from manure sources

Spray strategies to control Anthracnose fruit rot in day-neutral strawberries, 1994

Day-neutral strawberries were planted on 17 and 18 May 1994 in sand loam soil (fine , loamy, mixed mesic, Typic Hapludoll) at the Iowa Stale University Ho11iculture Faim near Gilbert, IA. Plants were spaced I ft apart in double rows with S ft between rows. Experimental design was a randomized complete block with !en treatments and four replications. Treatment subplots within blocks were 20-ft row segments. Treatment rows were alternated with guard rows. On 21 Jun, each subplot was inoculated with three ripe he1Ties displaying symptoms and signs of infection by~. acutatum, one beffY at either end of the subplot and one in the middle. All blossoms were removed until 7 Jul. Treatments were combinations of liming of application of fungicides (Benla!e SO WP, 8 ozJI 00 gal,+ Caplan SO WP, 3 lb/ I 00 gal) or of Gliocladium roseum(Peng and Sutton, Can. J. Plant Palhol., 13:247-2S7 , 199 1) and type of mulch (white-on-black plastic or straw). Guard rows were sprayed weekly with Benlate SO WP and Caplan SO WP, beginning on I Jul. Chemical fungicides or Q. roseum were applied lo runoff using a Solo backpack sprayer (Model No. 42S) with a flat-fan nozzle al approximately 30 psi pressure. Wetness duration and air temperature data for a postinfeclion disease-waining model (based on data of Wilson el al., Phytopathology 80: 111-116, 1990) were recorded hourly by a CR I 0 da!alogger and appropriate sensors (Campbell Scientific, Logan, UT). Ripe fruit were picked by hand, counted, weighed one to three times/wk, and be1Ties with symptoms of anthracnose rot were counted and weighed.</p