Does fertilizing corn with poultry litter enrich the grain with mineral nutrients

Authors: Tewolde, Haile; Sistani, Karamat; Feng, Gary; MENKIR, ABEBE - International Institute Of Tropical Agriculture (IITA)

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/11/2019
Publication Date: 6/27/2019
Citation: Tewolde, H., Sistani, K.R., Feng, G.G., Menkir, A. 2019. Does fertilizing corn with poultry litter enrich the grain with mineral nutrients. Agronomy Journal. 111:1-3. https://doi.org/10.2134/agronj2019.02.0094.
DOI: https://doi.org/10.2134/agronj2019.02.0094

Interpretive Summary: Poultry litter is a rich source of all mineral elements essential for healthy plant growth. Its use as a fertilizer in crops such as cotton and corn is known to enrich the soil and plant parts with phosphorus (P), potassium (K), magnesium (Mg), iron (Fe), zinc (Zn), and other mineral elements which litter is known to supply. Whether poultry litter enriches the corn grain with these elements, however, is not known. Enriching the corn grain with mineral elements, Fe and Zn in particular, would have human and animal nutrition implications. The objective of this study was to determine whether fertilizing corn with poultry litter increases the levels of mineral elements in the grain beyond that possible with convention fertilization with synthetic fertilizers. We grew corn in the field in northern Mississippi with no fertilization, fertilization with four or eight tons/acre litter, or conventional synthetic nitrogen (N) fertilizer. Then we took samples of soil, corn leaves, and corn grain and analyzed the samples for mineral element contents. As expected, fertilizing corn with poultry litter elevated the levels of soil N, P, K, Mg, Zn, copper (Cu), and manganese (Mn) by up to twofold relative to fertilizing with synthetic N. Litter also increased concentration of N, P, Cu, and Zn in corn leaves and stems. We also expected the level of some of the elements in the corn grain to be elevated by litter fertilization, but the results showed that applying relatively high amounts of poultry litter to corn does not enrich the grain with any of the mineral elements in proportion to the level of supply. The only element that enriches the grain in response to the level of supply is N. Grain N or protein increased in direct proportion to the amount of applied N whether the N was derived from poultry litter or synthetic N fertilizer. Grain P, K, Mg, Fe, Zn, and Mn in turn increased in direct proportion to the grain N content. This suggests that optimal N fertilization (in place of biofortification) may be the best approach to produce not only optimal corn grain yield but also to produce nutritious grain. Conversely, N nutrition insufficient for optimal grain yield leads not only to yield penalty but also to a reduction of the level of important mineral elements. The results have direct implications for corn produced for food and feed particularly in countries with chronic mineral nutrient deficiencies in human diets.

Technical Abstract: Whether poultry litter (PL) increases concentration of selected mineral elements in the corn grain has not been well investigated and documented. The objective of this study was to determine whether fertilizing corn with PL applied in the fall or spring enriches the grain and other plant parts with selected mineral elements. Corn was grown in the field in northern Mississippi with no fertilization (UTC) or fertilization with 9 Mg ha-1 PL, 18 Mg ha-1 PL, or 202 kg ha-1 NH4NO3-N applied in the fall vs. spring. Poultry litter, regardless of application timing, increased soil total N and extractable P, K, Mg, Cu, Mn, and Zn by up to twofold relative to NH4NO3-N. Litter also increased concentration of N, P, Cu, and Zn in leaves and stems but did not particularly enrich the grain with any of the measured elements. Grain N, P, K, Mg, Fe, Mn, and Zn concentrations were highest in corn fertilized with 202 kg ha-1 NH4NO3-N applied in the spring. Poultry litter increased grain concentrations of these elements to equal those of the NH4NO3-N fertilized corn only if it also increased the N level in the plant and the grain. High positive correlation of grain N with grain P, K, Mg, Fe, Zn, and Mn suggests that conditions that increase grain protein level would also increase the levels of P, K, Mg, Fe, Zn, and Mn in the grain if sufficient levels of these nutrients exist in the soil. Grain Ca, Cu, and Na were not affected by the treatments or by N nutrition of the corn plant. The results overall show that the level of mineral elements in the grain of corn fertilized with PL is dependent on the level of N nutrition of the plant rather than on the amount of the elements supplied by PL or the soil.