|Bruns, Herbert - Arnold|
Submitted to: Communications in Soil Science and Plant Analysis
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/10/2005
Publication Date: 11/25/2005
Citation: Bruns, H.A., Ebelhar, W. 2005. Nutrient uptake of maize affected by n and k fertility in a humid sub-tropical environment. Communications in Soil Science and Plant Analysis. 2006. 37:275-293. Interpretive Summary: Corn production in the Mississippi Delta has more than doubled in acres grown during the past 10 years, while yields per acre have increased by over 30%. Corn hybrids grown in the area have been bred for higher yields and information on the best nitrogen and potassium fertility rates for these hybrids is limited. An experiment has been completed at the Delta Research Center by USDA and Mississippi State University scientists to determine the concentrations and total contents of nutrients in corn plants grown under irrigation with various levels of nitrogen and potassium fertilizer, and following cotton. Nitrogen fertility rates of 120 to 280 lbs nitrogen per acre increased the concentration of nitrogen in all the plant organs analyzed and the total nitrogen content of the ear leaves, grain and stover. Yields, kernel weights, test weights, and harvest indices were also increased with increased nitrogen fertility. The concentrations of several micronutrients were increased with increased nitrogen fertility. Based on our data between 170 to 380 lbs of nitrogen per acre was removed by harvesting and marketing the grain in this study which yielded between 134 to 238 bushels per acre. Using the formula employed by Mississippi State University for determining nitrogen fertility rates for growing corn throughout the state, (1.3 lbs of nitrogen per bushel for the 1st 100 bushels per acre then 1.7 pounds per bushel for each additional bushel per acre) these grain yields would have required 188 to 365 lbs of nitrogen per acre, respectively. Our data confirms the current recommendation by Mississippi State University for nitrogen fertilizer on corn is accurate for the Mississippi Delta. Over 350 lbs of nitrogen per acre can be contained in the stover. Burning the stover after harvest should not be done due to the potential loss of the nitrogen to future crops. Potassium fertility had little effect on the nutrient concentrations of most other elements. Corn receiving potassium fertilizer did have higher concentrations and total contents of potassium in the ear leaves and stover than plots that received no potassium fertilizer. But these increases did not result in higher grain yields. Potassium is essential for good plant growth in corn by regulating the water status of the plant and promoting overall growth, but based on our data, rates above 40 lbs of potassium per acre in the Mississippi Delta do not benefit the crop.
Technical Abstract: Maize production is highly dependent on plants having adequate levels of nutrients. An experiment to determine the [N], [P], [K], [Ca], [Mg], [Fe], [Mn], [Zn], and [Cu] and contents of maize grown using N-fertility levels of (134, 179, 224, 269, & 314 kg N ha-1) in combination with K-fertility levels of (0, 45, 90, & 134 kg K ha-1) was conducted in 2000 and 2001 at Tribbet, MS. Ear leaves, immature ears, and husks collected at growth stage R2 and grain and stover collected 21 d post-R6 were dried, weighed, and analyzed for nutrient concentration. Plots were also harvested for yield, kernel weight, grain bulk density, and harvest index. Increased N-fertility increased [N] of all plant organs and the total N content of the ear leaves, grain and stover. Yields, kernel weights, grain bulk densities, and harvest index were also increased with increased N-fertility. Several micronutrient concentrations and contents also increased with increased N-fertility. Increased levels of K-fertility had only limited influence on concentrations of most nutrient elements. Only the nutrient contents of most of the elements in the stover increased with increasing K-fertility. With the exception of the total content of P in the stover, [P] and total contents of P were unaffected by the N and K-fertility treatments used in this experiment.