ISSN:
1573-0867
Keywords:
ash
;
Côte d'Ivoire
;
lime
;
mineral fertilizers
;
soil pH
;
apparent recovery fraction
;
relative effectiveness
;
shifting cultivation
;
subsitution rate or value
;
Taï National Park
;
upland rice
Source:
Springer Online Journal Archives 1860-2000
Topics:
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Abstract An important reason for burning the slashed vegetation in shifting cultivation systems is the release of nutrients. In an experiment in the Taï region, S.W. Côte d'Ivoire the fertilizing effects of ash and mineral fertilizers were compared. The ash was derived from a 20-year-old secondary forest which was slashed, dried, piled together and burned. The nutritional value of ash was compared with that of N, P, K fertilizers and lime in a field trial consisting of a “fertilizer” portion and an “ash” portion. The experimental design of the fertilizer portion was a 34 factorial. The application rates per ha were 0, 50, 100 kg N (urea); 0, 12.5, 25 kg P (triple superphosphate); 0, 50, 100 kg K (KCl); 0, 400, 800 kg Ca(OH)2. The 81 treatment combinations were divided into nine subblocks. To each of these subblocks three experimental units were added. In six of them ash was applied at rates of 0, 4000 and 8000 kg ash ha−1. With 4000 kg ash ha−1 31 kg P, 264 kg K, 915 kg Ca, 150 kg Mg, 10 kg Na, 10 kg Mn, 2.6 kg Zn and 32 kg S were applied. Upland rice (cultivar IDSA 6) was grown as test crop. The grain yields on individual experimental units varied from 1.2 to 3.2 t ha−1. In the 34 trial, N and P application significantly affected the yields of grain and straw. P application increased the uptakes of N, P, K, Ca and Mg significantly. N uptake was also significantly increased by N application and liming. There was a significant negative quadratic P effect on grain and straw yield, and uptake of nutrients, indicating that higher application rates did not result in higher yields and uptake of nutrients. Ash application significantly increased the yields of grain and straw and the uptakes of N, P, K and Mg, but not of Ca. It was concluded from the two trials that the response to ash application was mainly a P effect. The recovery fractions of P at about the same P applications rates were 7.4% and 11%, in the ash and 34 trial, respectively. Hence, the relative effectiveness of ash-P was 0.67 or 67%, and the substitution rate 1.5. This implies that for the uptake of a unit of P about 1.5 times as much ash-P as fertilizer-P should be applied. The effectiveness of ash as liming material was 0.59 compared to Ca(OH)2, hence 1.7 times as much ash as Ca(OH)2 is needed to establish a same increase in pH. The CaO equivalent of ash proved to be 44% and the CaCO3 equivalent 78%. In the ash trial a higher efficiency of utilization of absorbed P was found than in the 34 trial. Several possible causes of this difference are discussed but no conclusive answers could be given.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00749875
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