The need to be able to estimate the value of manure as crop nutrient source is the result of increased use of manure to replace crop nutrients that have long been supplied by commercial inorganic fertilizers.
“As with inorganic fertilizers, the goal is to meet the crop nutrient needs while avoiding the expense and potential environmental concerns of over-application of nutrients,” said Dharmendra Saraswat, associate professor and extension engineer for the University of Arkansas System Division of Agriculture.
To answer this need, the University of Arkansas Division of Agriculture has released the Manure Valuator app to help producers calculate the dollar and nutritive value of manure applied to a specific field and then share the results via e-mail. The app is now available for use on both iOS (iPhone and iPad) and Android devices.
The app was developed by Saraswat, in collaboration with Karl VanDevender, a professor and extension engineer, both in the Department of Biological and Agricultural Engineering.
The app is based on a simple premise that the monetary value of manure is linked to the market value of the inorganic nitrogen (N), phosphorus (P), and potassium (K) fertilizer that the manure is replacing. This means the value of manure depends largely on the crop N, P, K fertilizer recommendation, the manure N,P,K content, and the amount applied.
The app allows the user to enter the cost of his or her local commercial fertilizer source on either a dollar per ton or a dollar per pound basis. If dollar per ton values are entered, the app converts them to dollars per pound of nitrogen, phosphorus, and potassium.
The user then enters the crop’s N, K, and P needs, ideally based on recent soil test recommendations available though the county Cooperative Extension Office.
The user then selects one of 18 different choices of dry and liquid manure. If desired, the default N, P, K values can be modified to better reflect the manure to be applied.
After the desired manure application rate is entered, the app calculates the N, P, K fertilizer replacement value for the
specific field crop based on N, P, K recommendation, manure source, and manure application rate. At this time, any input value can be modified to evaluate the impact on the resulting calculated values.
Users of the Manure Valuator app have quick access to several useful features:
- a bulk cost calculator to determine cost per pound of nitrogen, phosphorus and potassium from inorganic fertilizers
- a database consisting of nutritive value of 18 different sources of manure that allows users to enter custom values for dry and wet manures
- a dictionary page that has been provided to explain each step used in the app
Funding for the app was provided by the Arkansas Corn and Grain Sorghum Board and the Arkansas Soybean Promotion Board.
The Manure Valuator app is available for free at iTunes (see https://itunes.apple.com/us/app/manure-valuator/id757582921?ls=1&mt=8) and Google Play Store (see https://play.google.com/store/apps/details?id=uaex.edu.manurecalculator&hl=en).
Users can also install the app on their mobile device by scanning the code found in the news archives at www.uaex.edu.
For more details about crop production, contact your county extension office or visit www.uaex.edu.