Do new corn hybrids and yield levels influence potassium fertilizer management?

The frequency of potassium (K) deficiency symptoms in corn has increased in recent years. Observations in Iowa and neighboring states have shown that the reason for these symptoms was a low soil K level in about two-thirds of the instances reported. In the rest of the instances, however, the K deficiency symptoms resulted from a variety of reasons related to limitations in root growth or water uptake and/or K uptake by plants. It is known that factors that limit root activity and growth greatly inhibit K uptake and yield because K is a relatively immobile nutrient in soils. A strong root system and continuous growth of fine roots are required to supply sufficient K to high yielding crops. However, there has not been research on K use efficiency or K fertilizer need of genetically modified modern hybrids with traits that may directly or indirectly affect the physiological needs for K or the plant capacity for K uptake. Of particular interest is the rootworm resistance trait, because a healthier root system without a need for root insecticides and higher yield could result on different root size or surface area that, in turn, can affect K uptake and the yield response to K fertilization. Therefore, a research project has been investigating since 2006 the K nutrition of corn hybrids with or without the rootworm resistance trait

Potassium Fertilization Rate Effects on Soil-Test Potassium and Yields of Corn and Soybeans

A 3-yr study was conducted to assess the effects of several potassium (K) fertilization rates on grain yield, K removal by corn and soybean, and soil-test potassium. This study complements long-term experiments at the farm that include fewer K application rates. The Iowa State University (ISU) soil-test K interpretations and fertilization guidelines were updated in 2003 based on research in many Iowa fields. One major change was to increase the soil-test potassium (STK) level suggested for optimum crop production. The category previously deemed Optimum, which ranged from 91 to 130 ppm (ammonium-acetate or Mehlich-3 K tests, 6-in. samples), was changed to Low, and the High category (131 to 170 ppm) was reclassified as Optimum. Fertilization with K is recommended to maintain this level

Effect of Potassium Fertilization and New Corn Hybrids on Yield and Potassium Uptake in Continuous Corn

A three-year study was conducted to evaluate the effects of potassium (K) fertilization and new corn hybrids resistant to rootworm on grain yield and K uptake in continuous corn. New corn hybrids may increase yield and change K uptake or fertilization needs through improved traits that increase yield and root efficiency. Therefore, this study was planned to test this hypothesis by comparing continuous corn yield and response to K fertilization of hybrids with and without the rootworm resistant trait

Corn Grain Yield and Potassium Uptake and Recycling as affected by Rootworm Resistance and Potassium Fertilization

New corn hybrids increase yield and may change potassium (K) uptake or fertilization needs through improved traits that increase yield and root efficiency. Hybrids, soil conditions, and rainfall may affect the rate at which K in cornstalks is released to the soil and becomes available to plant uptake. Therefore, a study was conducted from 2006 through 2009 at the Agronomy and Agricultural Engineering Research Farm to evaluate the effects of K fertilization and rootworm resistance on grain yield, K uptake, and K recycling with residue

Resurrecting the alien director: Jean-Pierre Jeunet in Hollywood

This essay examines the critical reception of Jean-Pierre Jeunet's Alien Resurrection in the popular Anglo-American press, where the film was often discussed in terms that highlighted the director's status as an 'outsider'. The anxiety that the film elicits among critics, it is argued, is a function of the very abjection that is depicted graphically within the film: a fear of the unclassifiable and of the crossing of boundaries

Effect of Potassium Fertilization and New Corn Hybrids on Yield and Potassium Uptake in Continuous Corn

A three-year study was conducted at this farm to evaluate the effects of potassium fertilization and new corn hybrids resistant to rootworm on grain yield and potassium uptake in continuous corn. New corn hybrids may increase yield and change potassium (K) uptake or fertilization needs through improved traits that increase yield and root efficiency. Therefore, this study was planned to test this hypothesis by comparing continuous corn yield and response to K fertilization of hybrids with and without the rootworm resistant trait

A New Long-term Study: Evaluation of Hybrid, Nitrogen, and Potassium Interactions in Continuous Corn

A long-term experiment was established in 2009 to study continuous corn responses to potassium (K), nitrogen (N), and hybrid rootworm resistance. Previous research suggested a need for this type of study in Southeast Iowa. A long-term trial conducted until 2001 at the Northern Research Farm in a soil testing low in P and K showed that N, P, and K fertilizers greatly increased corn yield but there was an interaction only between N and K. The maximum corn yield level, the relative yield response to N (percent increase for each N addition), and the N rate that maximized yields were highest when K was optimal or higher. In contrast, the relative yield response to N and the N rate that maximized yield were similar for soil-test P levels ranging from very low to very high. Ongoing studies at this research farm and four other farms show that rootworm resistance often increases yield compared with untreated susceptible hybrids. It does not affect the yield response to K consistently, but increases K removal because of the higher yields. Therefore, this new long-term study evaluates possible interactions between corn rootworm resistance, N fertilization, and K fertilization

Cutaneous melanoma and sentinel lymph node biopsy; An epidemiology study of population level data

Aims: Cutaneous melanoma accounts for 90% of all melanoma cases diagnosed. In addition, the incidence of cutaneous melanoma is increasing by approximately 3-7% yearly, and it is the most rapidly increasing cancer diagnosed in white populations worldwide. The aim of this study is to assess the survival benefit of Sentinel Lymph Node Biopsy (SLNB) in cutaneous melanoma in an Irish population. Methods: Population based data was obtained from the National Cancer Registry of Ireland (NCRI) on all patients with a cutaneous melanoma diagnosed over a 20-year period 1994-2014 and predictors of Overall Survival (OS) were assessed. Results: 13302 patients were identified with a melanoma diagnosis between 1994-2014. OS varied with gender, age, smoking and marital status, anatomical location and TMN stage. 2196 (17%) patients underwent SLNB, which included 710 patients in the stage 1 melanoma category (<11% of this group). Undergoing a SLNB was not an independent predictor of improved OS (p=0.440). However, a positive SLNB result was an independent predictor of OS (0.001). Conclusion: This Irish population-based data re-affirms demographic indicators of poorer survival. A positive SLNB result indicates poorer survival; however, the precedent itself is not a predictor of OS