ISSN:
1573-5036
Keywords:
Basal fertilizer application
;
Method of N application
;
Critical N level
;
Efficiency of fertilizer use
;
N transformation
;
N fertilizer source
Source:
Springer Online Journal Archives 1860-2000
Topics:
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Summary The importance of initial exchangeable soil NH 4 + in nitrogen nutrition and grain yield of rice was studied in a number of representative lowland rice soils in the Philippines. The initial exchangeable soil NH 4 + +fertilizer N plotted against nitrogen uptake by the crop resulted in a highly significant linear relationship (R2=0.91), suggesting that the presence of exchangeable NH 4 + in the soil at transplanting behaved like fertilizer nitrogen. The correlation between N fertilizer rate and N uptake by the rice crop was relatively poor (R2=0.73). On the other hand, relative grain yield was more closely correlated with the initial exchangeable soil NH 4 + +fertilizer N than with fertilizer nitrogen applied alone. These results indicate that the initial exchangeable NH 4 + in the soil contributed substantially to the nitrogen uptake of the crop. Critical nitrogen levels in the soil defined as the initial exchangeable soil NH 4 + +fertilizer N at which the optimum grain yield (95% of the maximum yield) is obtained, varied from 60 to 100 kg N/ha in the wet season and from 100 to 120 kg N/ha in the dry season for the different fertilizer treatments. The results further suggest that the initial exchangeable soil NH 4 + should serve as a guide in selecting an optimum nitrogen fertilizer rate for high grain yields.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF02145461
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