Assessment of Soil Potassium Supplying Capacity from Soil Nutrient Reserves and Dissemination of Nutrient Management Technologies through Nutrient Manager
Information generated from this project would help develop soil based coefficients on allowable draw down of soil K reserves, which can be used with Nutrient Manager for rice and maize in the determination of their fertilizer K requirements and for their dissemination.
IPNI-2010-BGD-6
24 Feb 2012
2011 Annual Interpretive Summary
Assessment of Soil Potassium Supplying Capacity from Soil Nutrient Reserves and Dissemination of Nutrient Management Technologies through Nutrient Manager, 2011
The current project was initiated to estimate the magnitude and variation in soil K supplying capacity across a range of soils growing intensive rice-maize system in Bangladesh. Eighteen soil samples were collected from Dinajpur, Rangpur, Bagura, Rajshahi, Nawabganj, Sirajganj, Tangail, Faridpur, Jhinaidah, Sathkhira, and Comilla districts, representing diverse mineralogy and properties related to soil K supplying capacity. The samples were analyzed for pH, organic carbon, total N, available P, exchangeable K, S, Zn, Mg and Ca. The exchangeable K in the samples ranged from 0.149 to 0.317 cmol/kg.
A pot experiment with rice was conducted in the above soils with two treatments, Zero K (K0) and 100 mg K/kg soil (K100), in four replications. Other limiting nutrients were applied at a set dose so that the plants are not in deficient in any other nutrient except K. Rice seeds were sown and allowed to grow up to the booting stage, and then harvested. Plant height, numbers of tillers, and dry weight of plant and root were determined from each pot.
Dry matter yield in the K applied pots was significantly higher than the K omission pots in 7 out of the 18 studied soils. There was poor relationship between soil exchangeable K contents and dry matter yield of rice. The dry matter yield range in the K0 and K100 pots were 10.1 to 33.3 g/pot and 14.8 to 39.2 g/pot, respectively. Analysis of the plant sample for K and other nutrient are in progress. After harvesting the first crop, soil in each pot was mixed and 15 days aged seedlings of rice were transplanted on December 4, 2011, in each pot as second crop. In a separate experiment, maize seeds were sown on November 10, 2011, which is now in V6 stage. Maize will be harvested at V8 stage and yield parameters as well as nutrient uptake will be analyzed. Both rice and maize will be grown for 6 to 8 crop cycles in the same pot to estimate K supplying capacity of the soils. The results from the pot experiment will be validated in two field experiments with five different rates of K in the upcoming rabi maize and boro rice. Bangladesh-006