Effects of phosphorus addition on growth of white clover Trifolium repens growing on ground calcitic limestone-treated colliery spoil from Higher Folds, Greater Manchester, England
Published source details
Costigan P.A., Bradshaw A.D. & Gemmell R.P. (1982) The reclamation of acidic colliery spoil. III. Problems associated with the use of high rates of limestone. Journal of Applied Ecology, 19, 193-201
Published source details Costigan P.A., Bradshaw A.D. & Gemmell R.P. (1982) The reclamation of acidic colliery spoil. III. Problems associated with the use of high rates of limestone. Journal of Applied Ecology, 19, 193-201
When reclaiming acidic pyritic colliery spoil, in order to neutralize acidity generated by iron pyrites oxidation, incorporation of ground limestone is required. However, growth of white clover Trifolium repens on such spoil has been shown to be inhibited by large applications of agricultural ground calcitic limestone. This may pose difficulties in establishment and maintenance of grass swards as these spoils contains no plant-available nitrogen so there is often a reliance on nitrogen fixation by leguminous herbs, e.g. clovers, to counter this problem. It is also possible that the inhibitory factors involved may restrict soil nitrification processes. In this study the effects of high and low rates of ground limestone incorporation and compensatory effects of phosphorous fertilizer addition on T.repens growth were assessed.
Acidic colliery spoil (pH 2.9) from Higher Folds, Greater Manchester (National Grid ref. SD 684005) northwest England, was treated with ground calcitic limestone at rates of 10 and 100 t/ha and phosphorus at 87,262 and 786 kg P/ha (as superphosphate).
All treatments were sown with white clover (at a rate quivalent to 200 kg seed/ha) in 14 cm pots. All the treatments received 125 kg N/ha (as ammonium nitrate) and 52 kg K/ha (as potassium sulphate) and pots, placed in a glasshouse, were watered with deionized water as required. The experiment was a randomized block, replicated four times. Dry matter production was determined three times (at 11, 20 and 34 weeks).
Clover dry weight production 11 weeks after sowing showed that the inhibitory effect of excess limestone was reduced by high phosphorus fertilization. However, this effect disappeared within 34 weeks of treatment. This implies that high liming creates a temporary phosphorus deficiency in T. repens, either through immobilization in the spoil or because of some effect which increases its phosphorus requirement. Analysis of shoots at 11 weeks showed no significant correlation of yield with phosphorus content. This suggests that phosphorus was not, in fact, limiting growth or that there was an increased phosphorus requirement at high limiting rates. Calcium content showed a significant positive correlation with yield, indicating that the inhibitory effect of high liming was probably not caused by excessive calcium uptake. However, magnesium content was also significantly positively correlated with yield indicating that magnesium deficiency may contribute to growth inhibition at high liming rates. Evidence supporting this was obtained by examination of the amounts of ammonium acetate extractable Ca and Mg in freshly limed spoil, the Ca/Mg ratio being greatly increased at the high liming rate.
Conclusions: The inhibitory effect of high limestone application on white clover was reduced by high phosphorus fertilization but this effect disappeared within 34 weeks of treatment. There was a significant negative correlation between potassium (K) content and yield. This may be due to an increased uptake of K in response to magnesium deficiency. There was evidence that high liming caused an imbalance of the Ca/Mg ratio in freshly limed spoil contributing to growth inhibition.
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