Nutrient Deficiencies in Agricultural Soils of the Wet and Intermediate Zones of Sri Lanka
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Date
2001-11-16
Authors
Kumaragamage, D.
Indraratne, S. P.
Journal Title
Journal ISSN
Volume Title
Publisher
University of Peradeniya,Peradeniya, Sri Lanka
Abstract
The inherent low fertility status of most agricultural soils in Sri Lanka makes nutrient
deficiencies a serious problem for profitable crop production. At present, few farmers are using
soil test-based fertilizer recommendation, considering only N, P, K and Mg deficiencies. Soils are
usually not tested for deficiencies of S and micronutrients and these nutrients are therefore not
supplied by majority of the farmers. Deficiencies of Sand micronutrients however have been often
reported for various crops in different' parts of the country.
This study was conducted to examine the available nutrient status and identify the nutrient
deficiencies in major agricultural soils of Sri Lanka. Soil analyses along with sorption studies and
a greenhouse experiment using a modified missing element technique were conducted to identify
nutrient deficiencies in 20 soils located in the Wet and Intermediate zones of Sri Lanka. Soils used
included Alfisols, Ultisols, Inceptisols and Entisols, which were under major agricultural crops.
Soil samples were analyzed for important physical and chemical properties and available nutrients,
i.e, N, P, K, Ca, Mg, S, Fe, Mn, Cu, Zn and B using standard techniques. Sorption studies were
carried out to determine the capacity to retain nutrients by soils. A greenhouse experiment was
conducted using a modified missing element technique, in which, the nutrients were supplied
based on the nutrient content and adsorption characteristics of soils. The fourteen treatments
included an optimum treatment (where all nutrients and CaCO3 were provided), twelve treatments
with one for each missing element (N, P, K, S, Ca, Mg, Fe, Mn, Cu, Zn, B and Mo) and one
treatment without CaC03. Sorghum was used as the indicator plant. Treatments were arranged in
a randomized block design with four replicates. The plants were harvested and dry weights were
taken after 4 weeks.
According to soil analysis, all soils were acidic in reaction with pH values ranging from 4.7
to 6.8 with low cation exchange capacities and low organic matter contents. Soil analysis for
nutrients indicates that experimental soils are very poor in fertility. All soils were deficient in N
and B. Most of the soils were deficient in P, K and S as well. Only one soil showed sufficient level
of K while only 3 and 4 soils showed sufficient levels of P and S, respectively. Few soils were
deficient in Ca and Mg, while in some, micronutrients were at deficient levels. Results of the
greenhouse study clearly indicated deficiency of N, P and in some soils S and micronutrients. The
dry weights of the final harvest were significantly (p<O.05) lower than in the optimum treatment in
treatments without N and P in most soils. Boron deficiency was indicated by soil results, but no
symptoms were seen in plants. Deficiencies of Fe and Zn were observed in a few soils. The
results indicate the importance of diagnosing nutrient deficiencies and balanced fertilizer'
application including S and micronutrients for profitable crop production.
Description
Keywords
Agricultural , Nutrient , Wet , Zones , Soil
Citation
Proceedings & abstracts of the Annual Research Sessions 2001,Unviersity of Peradeniya, Peradeniya, Sri Lanka,pp.05