Prognosis of boron deficiency in oilseed rape (Brassica napus) by soil analysis
Wei, Y., Bell, R.W. and Yang, Y. (2002) Prognosis of boron deficiency in oilseed rape (Brassica napus) by soil analysis. In: Goldbach, H.E., Rerkasem, B., Wimmer, M.A., Brown, P.H., Thellier, M. and Bell, R.W., (eds.) Boron in Plant and Animal Nutrition. Kluwer Academic Publishers, Dordrecht, The Netherlands, pp. 311-317.
Reliable prediction of boron (B) supply before planting can enable growers to avoid yield losses by applying fertiliser if required. Several reports indicate the successful use of soil analysis to evaluate soil B levels and predict their effects on growth and yield of crops (e.g. Morrill et al., 1977; Howeler et al., 1978; see also Bell 1997, 1999). Pre-planting soil analysis should be more effective than the present approach to B nutrient management in southeast China (Wang et al., 1999) which relies on foliar spraying of oilseed rape when symptoms appear on crops: such treatment is often too late to fully correct the yield loss from B deficiency (Z. Q. Ye and Y. Yang, personal communication). Studies also show that B concentrations in specific plant parts were well correlated with oilseed rape yield (Wei et al., 1998, also see Bell, 1997 for other examples). Whereas plant analysis can reflect B nutrient status in crops directly, there may not be sufficient time left in the season to make effective use of the information about a possible or actual deficiency. In such cases, soil analysis of samples taken before sowing is the most practical means of determining if B fertiliser is required.
The critical soil test values for B deficiency in crops are affected by many factors such as soil type, sampling depth, soil water, cultivars and other environment factors (Bell, 1997; 1999). In southeast China, farmers practise an annual rotation of oilseed rape and one or two crops of paddy rice. Paddy soil morphology and chemistry is profoundly affected by repeated cultivation in a wet state and by the redox reactions which occur when soils are saturated and then re-oxidised. The implications of this soil management system for forms and availability of B has not been studied in detail (Xu et al., 2001 ), neither have critical soil B test values been derived for prediction of B deficiency in oilseed rape on such paddy soils.
The present research was carried out in three soils commonly used in Zhejiang province, China for oilseed rape-rice rotations. Ten field experiments (Wei et al., 1998) were used to calculate the critical soil test values for predicting B deficiency in oilseed rape. In addition, 70 sites in two provinces were used to test the accuracy of prognosis using the derived critical range. In southeast China, extensive areas of low B soils are found (Liu, 1992). Thus, procedures for predicting B deficiency by soil analysis can be used to prevent yield loss in oilseed rape due to B deficiency.
|Publication Type:||Book Chapter|
|Murdoch Affiliation:||School of Environmental Science|
|Publisher:||Kluwer Academic Publishers|
|Copyright:||© Kluwer Academic|
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