Predicting Corn N response using Alkaline Mineralizable N and Haney Soil Health Tool-N
Nutifafa Adotey, Xinhua (Frank) Yin, and Ryan Blair
Nitrogen management in corn production in the US is essential considering more than half the total N fertilizer used in the US is applied in corn production. Given the substantial investment in N fertilizer and its potential environmental risks, implementing best N management practices has potential to improve efficiency and profitability of applications. Nitrogen fertilizer recommendations for corn in TN as well as most southern US are determined from N response trials and modified based on soil type, previous crop and crop production history. Current N fertilizer recommendation does not account for potentially mineralizable N; hence, there is a possibility for either over or under application of N fertilizer. Limited information is available on the adequacy of alkaline mineralizable N or the mineralizable component of Haney test to predict corn response to N on replicated small plots in producer field in southern US. A crop response to mineralizable N may help develop a site-specific N fertilizer recommendation tool for corn, thus avoiding over or under application of N fertilizer. Replicated small plot on-farm trials are on-going at two locations in west TN to address the adequacy of alkaline mineralizable-N and HSHT -N to predict corn N needs”. The objectives of the on-farm trials include: (1) evaluating the relationship alkaline mineralizable N and HSHT to corn response, (2) developing N fertilizer rate calibration using alkaline-hydrolyzable N, and (3) comparing current UT fertilizer recommendation, HSHT N fertilizer recommendation, and alkaline-hydrolyzable fertilizer recommendation.
Evaluation of Urease and Nitrification Inhibitors in Corn Production
Enhanced efficiency nitrogen fertilizers (EENF), recognized as a promising N management tool, reduces N loss, optimizes N uptake, improves crop productivity, maximizes profits, and reduces environmental pollution across various cropping system. Ammonia volatilization has long been recognized as a major N loss in several production system and among the factors that drive ammonia volatilization is application rates. Previous research on EENF often focus on either the recommended application rate or below the recommended. Research based on corn response to EENF for both granular and liquid fertilizers is limited, hence the necessity to address this knowledge gap. A trial is ongoing to compare the EENF to standard N sources among various N sidedress placement methods on ammonia volatilization and grain yield in an unirrigated no-till corn production system. Treatment combinations consisted of N sidedress application of (i) urea to ANVOL-treated urea, and SuperU at increasing application rates (ii) UAN to ANVOL-treated at increasing application rates. The objectives of this project include evaluating the 1) inhibitory effect of urease inhibitors on ammonia volatilization from urea-based N fertilizers at increasing application techniques and 2) impact of urease inhibitors at reduced and optimal N application rates on corn agronomic and yield at increasing application rates.