N-P-K FERTILIZATION EFFECTS IN AGRICULTURAL CROPS ON TWO DIFFERENT SOILS IN IDENTIC CLIMATIC LOCATIONS - 40 RESPECTIVELY 60 YEARS PERMANENT FIELD TRIALS AT LIMBURGERHOF

摘要

Yield reactions are shown of different agricultural crops resulting from two N-P-K nutrientdeficiency permanent field trials especially for the period 1970-1996. The 40 resp. 60 years permanent field are performed on two different soils but identic climatic locations. 1. The 60 years permanent field trial Limburgerhof, in particular with a relatively low humus content, penetrable top-soil of loamy sand and a very favourable, natural phosphorus later delivery capacity show the following results: 1.1While comparing the systems 'with/without livestock husbandry' the farmyard manure increases mostly the yield of sugar beet and potato in the treatments 'without N'. In corn the manuring with beet leaves exceeds in tendency the after effect of farmyard manure. 1.2 The P-K treatment shows only an insignificantly increased yield in comparison with unfertilized over the whole trial period. 1.3 The N-P-K and N-K treatments (without phosphorus) show a medium value for the systems for winter rye amounting to58 %, for corn and sugar beet 53 % each and for potatoes 33 % above the P-K treatment. Due to the high phosphorus supply capacity the N-K does not differ from the N-P-K, except corn and potato; corn above all in years with unfavourable weather conditions. 1.4 Depending on the systems for N-P-K and N-P (without potassium) there are significant yield differences ranging between 5 - 8 % for winter rye, corn and sugar beet; potato shows the most evident reaction on potassium deficiency in both systems, amounting to more than 15 %. 1.5 Furthermore, the comparison of different cultivars of winter rye and corn prove, that the more efficient cultrvar may use the full nutrient offer best in each case. 2. The 40 years permanent field trial Li'hof/Bruch on humussoil, in particular with low phosphorus and potassium values, but rich in organically bound nitrogen, has the following effects of N-P-K fertilization: 2.1 During the trial period the omission of any fertilization results in yield decreases of differentlevels inthe following order: Potato, sugar beet, corn, winter wheat, spring barley. 2.2 The P-K fertilization slows down the yield decrease in comparison to unfertilized but on a higher yield level. 2.3 The N-P-K fertilization results sustainably in the highestyield level among all crops. 2.4 Only at N-P fertilization the lacking potassium fertilization for potato and corn reaches a yield level-similar to the treatment without N-P-K. Especially for sugar beet the yield difference to N-P-K is below 10 %. 2.5 Only at N-K fertilization (without phosphorus) all crops react positively in comparison with the unfertilized in the beginning. Compared to N-P-K the yield difference increased during the trial period, for sugar beet from 11 to 60 %, for potato from 11 to28 % and for corn from 7 to 25 %. For cereals the P resp. K undersupply shows a different yield effect in the individual years. The reasons for that are subject to discussion. 3. In both permanent field trials the N-P-K fertilization has sustainably enhanced the harvest capacity of both locations and therefore, it contributed to a great extent to ensure the yield in unfavourable years. 3.1 The omission of P fertilization causes decreased yield results, especially for sugar beet on the humus gley, only.The sandy location rich in P has not shown any P harvest effect even after 60 years, expect from corn and potato. 3.2 The lacking K fertilization causes yield losses on both locations in comparison with N-P-K. It is important to mention that the value for that differs a lot depending on the respective crops. The most sensitive reaction was observed for potato and corn on the K fixing humus gley.