Nutrition problems in forest nurseries

Investigations commenced in 1945 by Crowther, in co‐operation with members of the Research Branch of the Forestry Commission, to analyse problems of soil fertility and plant nutrition in forest nurseries, are described. the investigations still continue. Results from many small‐plot experiments in several nurseries and seasons, with Sitka spruce as the main test crop, have shown that it is safe to use commercial fertilisers (such as ‘Nitro‐Chalk’, ammonium sulphate, superphosphate and potassium chloride) in seedbeds and transplant beds. In short‐term experiments, which tested a range of composts and uncomposted organic manures with and without additional fertiliser, the effects were related to the major plant nutrients present. Interim results for two long‐term rotation experiments, in which continuous conifer cropping was compared with conifer cropping interrupted by fallow or green crops, have up to now shown no benefit from the green crops. In the same experiments, averaging results of eight seasons, seedlings grown with fertiliser were slightly taller than those grown with compost. A symptom of needle tip‐burn, which occurs every season in a heathland nursery on a highly leached acid sandy soil, has been recognised as being due to copper deficiency and has been cured by a foliar application of Bordeaux mixture. In some older nurseries, often with soil of neutral or near neutral reaction, Sitka spruce and some other conifers remain stunted even with ample manuring. Although the cause of the failure is not yet understood, it has been possible to obtain good growth after soil acidification, and after application of steam, formalin and chloropicrin.