• The importance of accounting for unobserved heterogeneity, state-dependence and differences in residual variances across groups: An application to Irish Farmers land market participation decisions

      O'Neill, Stephen; Hanrahan, Kevin (Teagasc, Oak Park, Carlow, Ireland, 2010)
      Land is an essential input into agricultural production. A grwoing literature is concerned with the factors influencing farmers’ land market participation decisions in developing countries, with developed countries largely ignored. Current best-practise in the land market participation literature is exemplified by Holden et al. (2007) who use a dynamic model which allows for state-dependence and unobserved heterogeneity. Much of the literature fails to adequately deal with these features of land market decisions. In addition, a single model is used to represent all farm types. In this paper, we firstly consider the factors influencing land market participation decisions in a developing country, Ireland, while allowing for state-dependence, unobserved heterogeneity and differences across farm tyes. We compare these results to those that are obtained while ignoring state-dependence, unobserved heterogeneity and differences between farm types. Our results suggest that some caution may be warranted when these aspects are ignored when if fact they are present.
    • Phosphorus management on Irish dairy farms post controls introduced under the EU Nitrates Directive

      Buckley, Cathal; Wall, David; Moran, Brian; O'Neill, Stephen; Murphy, Paul N. C.; Department of Agriculture, Food and the Marine, Ireland (Elsevier, 08/11/2015)
      The Republic of Ireland was one of a minority of EU member states to include direct controls on chemical phosphorus (P) fertilisers in its EU Nitrates Directive National Action Plan, first introduced in 2006. This study estimates farm gate phosphorus balances and use efficiencies across 150 specialist dairy farms over the seven year period since these controls were introduced (2006–2012) using nationally representative data. Results indicate that P balances declined by 50% over the study period from 11.9 in 2006 to 6.0 kg ha− 1 in 2012. This decline was driven by a reduction in chemical fertiliser imports of 6.5 kg ha− 1. This is equivalent to a reduction of 281 kg of P and represents a cost saving of €812 per annum across the average farm. Phosphorus use efficiency also improved over the period from 60% in 2006 to 78% in 2012, peaking in 2011 at 88.3%. This was achieved while increasing milk solids output per hectare and per cow. Results of a random effects panel data model indicated that P balance and use efficiency are significantly influenced by factors such as fertiliser prices, stocking rates, land use potential, use of milk recording technology, contact with extension services and rainfall patterns.