Soil health and nutrient management
Permanent URI for this collectionhttp://elibrary2.sugarresearch.com.au/handle/11079/13842
Research outcomes: Soil health is improved with a resulting positive impact on the environment and yield growth. Improved reputation and relationship between industry and environmental groups.
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Item Acid sulfate soils in canegrowing regions of northern New South Wales(1995) Reghenzani, JRAcid sulfate subsoils contain iron pyrites (FeS2). Pyrites is stable under anaerobic (saturated) conditions, but when oxidised forms sufuric acid and releases mobile Fe2+ ion. Soil pH can be reduced to as low as 2 and aluminium is released into the soil solution. These conditions can be toxic for plants. Ground water from acid sulfate soils which finds its way to drains and streams, particularly after rainfall following extended dry periods, may kill aquatic life.Item Soil constraints to productivity improvement(1990) Croft, BJ; Magarey, RC; Hurney, AP; Reghenzani, JRYields of most crops are known to decrease if that crop is grown continuously without fallowing or rotation with other crop species. Sugarcane has been grown continuously on many fields in Queensland for 50-100 years. As early as 1934 soil-borne factors which restricted root and shoot growth were identified in fields which had grown sugarcane for a number of years. During the 1970s nematodes were found to be causing serious losses in Bundaberg on certain soil types and a serious root disease complex known as poor root syndrome was identified in northern Queensland. During the 1980s intensive research into poor root syndrome identified the important new disease Pachymetra root rot and a number of minor fungal pathogens. Poor root syndrome has been identified in all regions of Queensland and general poor root health has been noted in all soils which have grown sugarcane for a number of years. Yield increases of 50-100% were obtained in areas severely affected by poor root syndrome in northern Queensland by soil fumigation with methyl bromide and metham sodium, and by soil solarisation. Recent experiments have recorded yield responses of 20-40% to methyl bromide fumigation in all major sugarcane regions. These experiments suggested that yield losses due to soil-borne factors may be greatly restricting yields throughout the sugar industry. Research to identify the causes of the yield losses has commenced and progress to date is summarised in this paper.Item Soil constraints to productivity improvement(1991) Croft, BJ; Magarey, RC; Hurney, AP; Reghenzani, JREvidence from investigations into fumigation, fungicide application, fallowing and growth of sugarcane on recently cultivated soils strongly suggests that yields in established cane growing areas are being restricted by soil-borne biological factors. The yield restriction may be in the order of 20-40%. The soil-borne pathogens Pachymetra, Pythium and also nematodes probably account for a proportion of this yield loss, but other unknown deleterious microorganisms may be involved. In most cases nutrient deficiencies do not appear to be limiting growth. Zinc deficiency which has recently been identified in northern districts may be affecting growth on some soil types. Excesses of some nutrients, such as phosphorus may be interacting with other nutrients and/or soil-borne pathogens. A multi-disciplinary study of soil-borne limits to yield in sugarcane is needed to identify the major factors involved and to develop satisfactory treatments to ameliorate the problem.Item The effect of zinc deficiency as a factor limiting sugarcane growth (SRC Project BS14S - Final Report)(1990) Reghenzani, JRResults from this project confirm that substantial yield responses to zinc application can be expected in deficient soils in North Queensland. Deficiency is commonly associated with lime application. Three soil and two foliar analytical techniques have been evaluated for detecting zinc deficiency. Currently used critical levels for zinc in cane third leaves have been confirmed as the most reliable index of deficiency. The carbonic anhydrase assay on fresh leaf extracts shows promise for measuring active zinc and providing a rapid and reliable foliar index of zinc deficiency. Critical levels for soil zinc have been established for the standard DTPA extract and for two hydrochloric acid extracts. Both acid extracts are more reliable than the DTPA extract.Item Extent of zinc deficiency in cane growing soils of North Queensland.(1993) Reghenzani, JRCollation and interpretation of soil analysis data has shown a strong relationship between soil type and extractable zinc. Extractable zinc in soils followed the order: metamorphic, beach ridge and granite soils < organic and alluvial soils < basaltic soils. More than 15% (18 000 ha) of north Queensland sugarcane soils from Mossman to Ingham were estimated to be at risk from zinc deficiency and associated constrained productivity. This study has identified and mapped low zinc soils and remedial action can now be taken. While alternative zinc forms applied with planting fertiliser have a role, preliminary data from this project does not support a change in the recommended application technique of zinc sulfate heptahydrate, broadcast and incorporated before planting.