Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/27/2009
Publication Date: 1/1/2010
Citation: Tewolde, H., Adeli, A., Sistani, K.R., Rowe, D.E., Johnson, J.R. 2010. Equivalency of Broiler Litter to Ammonium Nitrate as a Cotton Fertilizer in an Upland Soil. Agronomy Journal. 102:251-257. Interpretive Summary: Poultry litter which is a mixture of chicken manure and bedding materials has been known to be an effective row crop fertilizer. Many farmers in the southeastern US, where much of the poultry litter in the US is generated, have started to consider poultry litter as a more economical alternative to commercial inorganic fertilizers for cotton and other row crops. But the decision on whether to switch to poultry litter has been made difficult because there is no easy way of determining its true value relative to commercial fertilizers. Currently, the easiest and most common way of estimating the value of litter is based on how much the nutrients N, P, and K it contains. But this method disregards many other benefits that litter provides to the soil and crops. In this research, we used a new approach that has not been used before and is more reflective of the actual value to a row crop farmer. The results showed that fertilizing cotton with about 1.6 tons per acre raw chicken litter produced the same lint yield as fertilizing with 80 lbs per acre N from ammonium nitrate fertilizer. Based on this equivalency, we determined the fertilizer replacement value of litter to be $78 per ton of raw litter which is about 28% more than the estimate ($61 per ton) based on the traditional method. Interestingly, applying more litter than the 1.6 tons per acre increased lint yield but applying ammonium nitrate more than 80 lbs N per acre did not increase yield. This shows cotton lint production can be increased above that possible with commercial fertilizers if fertilizing with the right amount of raw chicken litter. The results also show that chicken litter is substantially more valuable than can be accounted for by its N, P, and K content.
Technical Abstract: Estimating litter value based on crop yield equivalency to inorganic fertilization may reflect the actual value of litter more accurately than based on its N, P, and K content. The primary objective of this research was to identify broiler litter rate which results in equivalent cotton lint yield as optimal inorganic N fertilization rate and estimate litter value based on this yield equivalency. The research was conducted near Holly Springs in northern Mississippi in 2002 to 2004 in a Loring silt loam upland soil considered marginally productive. Cotton was fertilized with six broiler litter rates ranging between 0 and 13.4 Mg ha-1, six NH4NO3-N rates ranging between 0 and 168 kg ha-1, in a side-by-side comparison. Lint yield in this soil peaked at 1066 kg ha-1 when fertilized with 90 kg ha-1 NH4NO3-N or at 1161 kg ha-1 when fertilized with 6.7 Mg ha-1 litter. Fertilization with 3.7 Mg ha-1 litter produced lint yield equivalent to the optimal 90 kg ha-1 NH4NO3-N. The fertilizer replacement value of litter calculated based on this equivalency ($86 Mg-1 litter) exceeded the value calculated using the traditional method ($67 Mg-1 litter) by ˜27%. Cotton fertilized with broiler litter had less tissue N concentration and chlorophyll index, comparable leaf area index, but produced more lint than cotton fertilized with NH4NO3-N. Lint yield of cotton fertilized with the optimum 6.7 Mg ha-1 litter surpassed yield of cotton fertilized with the optimum 90 kg ha-1 NH4NO3-N by 95 kg ha-1 lint. These results overall show that fertilizing cotton in this soil with litter increase lint yield above that possible with conventional inorganic fertilization and that broiler litter is substantially more valuable than can be accounted for by its N, P, and K content.