Probit Model Analysis of Farmers' Decisions to Implement Recommendations for Manure Applications.

Distribution of manure on a farm is constrained by strategic, tactical and operational factors. These factors cause farmers to apply manure in different locations and amounts compared with the recommendations in a nutrient management plan (NMP).  The factors that affect a farmer’s choice to implement manure recommendations can be identified by econometric models such as a Probit model. Probit models were formulated using four or five years of field-by-field records of manure applications from four dairy farms in Connecticut. The results of the Probit models show that the farmers’ decisions about manure applications are significantly affected by a common factor: the distance from the manure storage lagoon to the field. The type of machinery used to transport the manure, whether a tanker truck or a tractor-pulled tank, also has such a significant effect on the transportation of the manure.  Other factors such as size of a field, crop, ownership of a field, soil test P, recommended manure application, fertilizer N and P applications, N and P requirements for crop growth, and the interaction term of distance and ownership also have a significant effect for some farmers on decision making. The results of the Probit models indicate that the dairy farmers make significantly different decisions about distribution of manure. Identification of the factors affecting a farmer’s decision is important for NMP writers and policy makers for developing more feasible and adoptable NMPs while minimizing the negative effects of land application of manure. This research illustrats how to use and to interpret the Probit model to analyze the behavior of decision makers who face two alternatives-a traditional practice or an improved practice.