Jan Prummel

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The results are given of an investigation in the Netherlands, made over a number of years, on placement of fertilizers. This new method of application has been tested in field trials, in which placement has been compared with the usual method of broadcasting at certain increasing levels of fertilizer. The experiments relate to nitrogen, phosphate and potash(More)
Changes in the soil phosphorus and potassium status on three farming systems in the Northeast Polder during 25 years are related to the fertilizer regime over this period. The changes in the nutrient status of the soil are reflected in fertilizer policy. High rates of phosphate dressings markedly increased the phosphate status of the soil and built up a(More)
The feasibility of using chemical plant analysis for early diagnosis of phosphate and potassium deficiencies in potatoes was studied. Plant tops (leaves including stems) were sampled from fertilizer field experiments and analyzed for total N, P and K. The inverse relationship between plant N concentration and plant age was used for correcting plant P and K(More)
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