Software PPBB_MX: Potential Productivity Modelling of Brachiaria Brizantha (Cultivars Marandu and Xaraés)

Recent improvements in computer capacity and technology allow models to be built to simulate the attributes of many agricultural processes and systems. Although Brachiaria brizantha is the most cultivated tropical grass species in Brazil, there is no single tool to predict its production under optimal conditions. The objective of this paper is to present PPBB_MX software to calibrate and simulate (using a stochastical procedure) the shoot and total biomass potential productivity (output variables) of Brachiaria brizantha as a function of the following input variables: local latitude, season (from cutting date - Julian day), length of regrowth (time, days) and climate attributes (global solar radiation and air temperature)

Optimising land use and water allocation in intercropping systems.

The main purpose of this study is to identify the optimum allocation of limited amount of land and irrigation water across a number of alternative farm enterprises, maximising the whole-farm profitability by considering present relative prices, changes in river water availability, irrigation system efficiency and a highly variable climate. It was developed an optimisation model by using linear programming language to maximise the whole-farm profit of farm located in Wee Waa (NSW, Australia), for three different scenarios (dry, average and wet years) over two seasons. The whole-farm profit is highly sensitive to climate variability and also to prices and yields variability, especially in relation to cotton