Purpose built standoff on dairy farms for environmental protection and efficient production : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Agricultural Science, Massey University, Palmerston North, New Zealand

Abstract

Farmers are increasingly concerned about pasture and soil protection and nutrient loss from their farms to receiving surface and ground waters. The practise of standoff using purpose built facilities is one potential solution to these twin problems. However, the adoption of standoff is expensive as it incurs numerous costs such as those associated with the construction of the feed and loafing areas and the handling of the extra volumes of effluent that are produced. This study investigates the implementation of standoff on four case study farms in the Manawatu region. One of the farmers is contemplating adopting standoff for soil and pasture protection, one of the farmers is considering the use of standoff to lower leaching from his farm while two of the case study farms are wondering about the use of standoff for both purposes i.e. soil/pasture and environmental protection. A range of tools was used to simulate the role and impact of standoff in the four cases study farms including; the soil water balance, the Farm Dairy Effluent Storage Calculator, Overseer and the DairyNZ investment tool. The soil water balance was used to identify the timing and extent of standoff, which are in turn important inputs into other the other models. The two major benefits of standoff in winter and spring for farm profitability are a potential increase in milk production and improved utilisation of supplements. Where standoff was practised for soil and pasture protection it was assumed that milk yield would increase by a relatively modest amount (10%) over the months August to October inclusive. The conservative nature of the analysis performed here recognises that the cases study farms are currently well managed. The simulations suggest that standoff for soil/pasture and environmental protection would be effective in helping the farmers meet these objectives. The case study farms with poorly drained soil would stand cows off for significant periods in order to protect soils and pastures. The cost of standoff is dependent on a number of factors. In this study, the impact of standoff on the costs associated with managing increased volumes of effluent were investigated in more detail. Standoff obviously results in the generation of more effluent. The costs associated with handling this effluent varied across the case study farms. Farms where large periods of standoff occurred in winter and where the effluent was irrigated to high risk soils required large increases is storage volume. Farms where standoff was only practised in summer and autumn to reduce leaching from free draining soils required very little increase in storage volume. The required expansion of the effluent block varied across the cases study farms but was typically 500 to 710 m2 per cow. Overseer suggests that standoff would decrease N leaching from the farms by 4 to 26%. The DairyNZ tool suggests that there is the risk that standoff will not be a good financial investment on the case study farms. Only one of the scenarios explored here had acceptable values for the financial parameters such as NPV. For all other scenarios, standoff was not a financially viable proposition. This would be expected for the farm where standoff was only practised over the summer and autumn periods as standoff at this time of the year has few other financial benefits. In this case, standoff should be compared with the cost of other mitigation options. Given the complexity of identifying the advantages and costs of standoff, any farmer contemplating adopting standoff needs to perform their own comprehensive and detailed analysis. If milk production is greater than the value assumed here or the standoff facility can be constructed and operated more cheaply than assumed here then standoff may well be a sound financial investment.