Bilbul irrigator, Darrell Fiddler, aims for the most profitable crop, which is not always the highest yielding. In the high water price years since 2013/14, the rice, cotton and winter cereal grower has been drill sowing rice and delaying the permanent water for up to nine weeks after the first flush.
Rice water depth management at microspore is critical in protecting the developing panicle from cold-induced floret sterility which can lead to large reductions in rice grain yield at harvest. At microspore, air temperatures below 15 to 17°C can damage the developing pollen, leading to floret sterility and yield loss.
Water budgeting is very important as there is a direct correlation between water use and profitability. It is recommended that you record and understand your historical rice crop water use levels for each specific paddock before making sowing decisions. Strategies can be implemented to reduce crop water use.
Low surface water irrigation allocations in recent years have led to the increased use of groundwater for rice growing. Groundwater usually has higher salinity than surface water. the salinity of surface water is measured using electrical conductivity (etc), and is usually below 0.2 dS/m (130 ppm).
Monthly water budgets to compare crop water requirements and available allocations are very important. If crop needs are likely to exceed supply then decisions about buying extra water or reducing the area of rice by draining must be made.
A replicated experiment was established at Yanco Agricultural Institute in October 2008 with rice being irrigated at a range of moisture stress levels until two weeks prior to panicle initiation when permanent water was applied.
Water depth markers are an essential tool for good establishment
Shallow water depth management during establishment of ponded rice crops is key to achieving high yields and water use efficiency. In shallow water, the seedling grows to the surface faster to commence photosynthesis to support more growth, better root development, develop biomass and less wind damage occurs, compared to seedlings in deep water.
Four years of investigation into delaying the application of permanent water on drill sown rice has proven the technique to be a viable water management option. Research conducted on both red-brown earth and self-mulching clay soils has shown that rice copes well with the moisture stress and that delayed permanent water leads to considerable water savings with only a small decline in grain yield.