Prognosis of Boron Deficiency in Oilseed Rape (Brassica napus) by Soil Analysis

Abstract

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, Bell 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.