Ground Cover Supplement : GC Supplement - Nutrient Management 2006
Ground covEr nutriEnt mAnAGEmEnt 12 ProjEct uPdAtE software sets the nutrient balance ProjEct: mAnAGinG nutriEnts to imProvE lAnd And wAtEr QuAlity miKE wonG tHe FirSt outPut of this nMi project, based in WA, is a simple software package to help growers carry out their own nutrient balance calculation at paddock scale. the project, which involves collaboration between CSiro, the Department of Agriculture Western Australia, the Fitzgerald river Catchment Demonstration initiative (FrCDi) and Murdoch university, has its field sites in the South Coast region near jerramungup, along the tributaries of the Fitzgerald river. the software allows the local growers to make their own calculations by: 1entering the name and amount of fertiliser used in the paddock. the software looks up a table to read the nutrient content of the fertiliser and calculates nutri- ent input from the amounts applied. 2entering the yield and type of crop harvested. the software looks up a table of crop nutrient content to calculate nutrient removal from the paddock. 3entering the soil type in the paddock, year and near- est town. the software uses this to estimate likely nitrate leaching from an APSiM simulation of crop growth and nitrogen use. 4For pasture, the software uses soil type and rainfall to calculate the amount of water used by pasture and calculates biomass production from water-use efficiency measurements in WA. the grower elects a pasture leg- ume composition which is then used to estimate nitro- gen input by fixation. 5For legume crops such as lupin, a harvest index is used to estimate post-harvest crop residue and nitrogen supply from its mineralisation. 6the software calculates and displays nutrient input, removal and balance. this can be used to highlight where imbalances exist over one or several seasons, ena- bling growers to take corrective action where necessary. the software is easy to run and had some road testing and positive feedback during the jerramungup Grower Group (jerAC) expo in october. A nutrient balance calculation allows the grower to assess if a paddock is losing or accumulating nutrients as a result of farming. this is important, because the natural reserves of nutrients are typically low in WA wheatbelt soils and depletion may lead to deficiency and loss of potential yield and profit. A good example is potassium. it is removed from the land at the rate of about four kilograms per tonne of cereal or 8kg/t of lupins or 9kg/t canola. Because potash was rarely used until recently, this resulted in depletion of the soil potassium reserves, development of wide- spread deficiency and yield loss. this problem is now well recognised and potassium has the fastest-growing fertiliser use in WA. Magnesium is being depleted from wheatbelt soils in the same way as was potassium. the implication of this depletion is yet to be assessed. in contrast, phosphorus is accumulating in many WA wheatbelt soils and if lost through erosion could affect water quality. the fieldwork at jerramungup assesses, at catchment scale, the source, mobilisation, transport and delivery of nutrients from farms to streams. it involves stream water monitoring for water flow and quality, soil sampling and farm surveys to calculate farm nutrient balances, remote sensing to spatially distribute catchment yield and mod- elling to identify and manage the sources of nutrient pollutants in the landscape. Water-quality monitoring this year shows phosphorus and nitrogen concentrations far in excess of Australian and new Zealand environment Conservation Council trigger values for south-west WA at all five monitored stream locations. the relative contributions of different potential sources to these high nutrient levels will be determined. We plan to then develop options for land and nutrient management that will enable growers and the catchment community to improve profit and maintain or enhance water quality. Dr Mike Wong is a senior research scientist at CSIRO Land and Water. grDC research Code CsO00034 For more information: mike Wong, 08 9333 6299. email@example.com linda lee, a local farmer and manager of the FrCDi project, discusses the nutrient balance calculator with nirav Khimashia of CsirO at Jerac expo 2005.
GC Supplement - Farm safety
GC Supplement - Precision Agriculture 2005