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Technical annual report 2000-01



Technical annual report 2000-01


Dept. of Regional Development, Primary Industry, Fisheries and Resources technical annual report; Department of Regional Development, Primary Industry, Fisheries and Resources technical and annual report; Reports; PublicationNT; Technical bulletin (Northern Territory. Dept. of Primary Industry and Fisheries) ; no. 295




Made available via the Publications (Legal Deposit) Act 2004 (NT).






Agriculture -- Northern Territory -- Periodicals; Fisheries -- Northern Territory -- Periodicals

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Dept. of Primary Industry and Fisheries

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Technical bulletin (Northern Territory. Dept. of Primary Industry and Fisheries) ; no. 295



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Technical Annual Report 2000/01 11 SUBPROGRAM: Irrigation Development PROJECT: Irrigated Maize Production on Blain Soils at Douglas Daly Research Farm Project Officers: F. O'Gara, C. Ham and S. Lucas Location: Douglas Daly Research Farm Objective: To determine the yield potential and agronomic requirements of irrigated maize in the Daly Basin. Background: Irrigated maize is currently grown by a small number of producers in the Katherine district. While the demand for maize revolves around a small local market, the potential of the crop has not been fully exploited by producers. Past commercial yields have been disappointing. Maize has the potential to provide producers with moderate to good returns, provided high yields are achieved. Maize can also be used in rotation with other irrigated crops to help reduce weed, insect and disease pests in farming systems. There is a need to evaluate the potential of irrigated maize in the Top End, to identify suitable varieties and develop specific agronomic recommendations for this area. The demand and returns for irrigated maize is likely to increase significantly if farmers can consistently produce high yielding crops. Irrigated maize production has been investigated at DDRF for the past three Dry seasons. Method: Selected maize varieties, provided by commercial seed companies are sown into a conventionally prepared seedbed between late Match and late April. Four replicates are sown in a randomised complete block design. The total area is approximately 5 hectares. Plot sizes are 150 m long by four rows. Hand and machine harvest samples are taken from each plot. Leaf samples are taken 35-40 days after sowing (DAS) and at silking to determine plant nutrient content. Fertiliser is applied pre-plant, at planting (banded) and by fertigation. The trial receives approximately 280 kg N, 40 kg P, 150 kg K, 33 kg S, 64 kg Mg, 20 kg Zn and 1.5 kg B depending upon soil analysis. Zinc and Mg are applied at high rates initially to avoid deficiency. Subsequent Zn and Mg applications are reduced. Average population is between 75,000 and 84,000 plants per hectare. An Environscan soil moisture-monitoring system and Jet-Fill Tensiometers monitor irrigation and soil moisture content. The crop receives about 4.8 ML of water. Primextra (atrazine plus metolachlor) is used post-plant pre-emergent to controls weeds. When threshold populations of insects such as armyworm, Helicoverpa spp. and green vegetable bug (GVB) are reached, they are controlled by recommended insecticides. 1999 Results: The crop showed early P and N deficiencies due to uneven banding of fertiliser at planting. This was caused by poor design of the fertiliser metering system. All varieties recovered shortly afterwards, as nutrients became available. Variety PAC338 had a significantly lower yield due to poor plant establishment (52,000 plants/ha), because of low seeding vigour. Pioneer 3237 was the highest yielding variety. The other seven varieties did not differ significantly in production. Insect pressure was high in 1999. Leafhoppers, plant-sucking bugs and various lepidopterous larvae were at damaging levels at specific periods during the season.