Assessment of Soil Potassium Supplying Capacity from Soil Nutrient Reserves and Dissemination of Nutrient Management Technologies through Nutrient Manager

Objectives and Justification:
ACIAR-funded rice-maize project is being conducted at 4 districts in Bangladesh since October 2008. One of the main focus of the project is the development and evaluation of site-specific nutrient management (SSNM) principles and tools for dissemination of fertilizer recommendations through Nutrient Manager for rice and maize, a software developed for profitable fertilizer recommendation. The project has made a lot of progress in improving our understanding of SSNM strategies across soil types in the project sites. The project is contributing data and intellectual inputs for conceptualization and testing of the Nutrient Manager. As a result, an advanced version of Nutrient Manager for rice and a prototype version for maize has now been developed and evaluated in several locations in the three project districts. The Nutrient Manager for rice has also been evaluated in the Cereal Systems Initiative for South Asia (CSISA) project sites in two districts in Central Bangladesh.

Of the three main macro nutrients (N, P, and K), much work has been done in the past about N management in cropping systems. P is generally in sufficient amount in Bangladesh soils as it is accumulated in the soil over the long run. K now seems to be quite important for 2 reasons: first, in many locations large amount of K is supplied through crop residues, especially rice residues, and irrigation water, and second, K fertilizer (e.g. MOP) is expensive and farmers tend to apply more K than required especially in rice-maize and rice-potato-maize systems. As a result, it may not be quite profitable to follow these cropping systems. It is hypothesized that soils differ in K in terms of mineralogy, soil K reserves, allowable draw down, and K supplying capacity. Thus, some soils would require more K while others would require less K to grow profitable rice and maize crops. Of particular importance and focus now is on K nutrition due to high demand of K by these crops. Carefully-conducted pot and field experiments would help estimate through a plant-based assay the magnitude and variation in soil K supplying capacity in soils. The information generated from such experiments 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 disseminations. Thus, the proposed Ph.D. research work will be conducted through pot and field studies with the following research objectives and work plan.

Objectives:
i. To estimate through a plant-based assay the magnitude and variation in soil K supplying capacity across a range of soils
ii. To relate plant-based soil K supplying capacity with soil properties across a range of diverse soils
iii. To develop soil-based coefficients (e.g., soil K supplying capacity, K draw down factor, etc.) on allowable draw down of soil K reserves, which can be used with Nutrient Manager in the determination of fertilizer K requirements for rice and Maize
iv. To disseminate fertilizer recommendations for rice and maize through Nutrient Manager.

Questions:

i. What forms of K will be depleted after several harvest of rice or maize: total, exchangeable, or non-exchangeable?
ii. How much non-exchangeable K goes to exchangeable K after several harvests?
iii. Does soil with low reserves deplete earlier than soil with high reserves?


Summary of work plan:

· Year 1 (1 July 2010- 30 June 2011):
§ Literature review
§ Start of pot studies from October 2010.

· Year 2 (1 July 2011- 30 June 2012):
§ Continuation of pot studies
§ Start of field studies from October 2011
§ Start writing of Ph. D. dissertation
· Year 3 (1 July 2012- 30 June 2013):
§ Training and assisting the Department of Agriculture Extension (DAE), NGOs and private sector personnel for the dissemination of fertilizer recommendations through Nutrient Manager for rice and maize
§ Writing and submitting Ph.D. dissertation
§ Writing and submitting at least 2 or 3 papers to international journals

Deliverables:

· The Ph.D. student will submit technical progress report to IPNI annually by 30 June of each year.
· The Ph.D. student, in collaboration with his supervisor at Bangladesh Agriculture university (BAU), Bangladesh Rice Research Institute (BRRI), Bangladesh Agricultural Research Institute (BARI), collaborators from the ACIAR rice-maize project, and with IPNI and IRRI scientists, will write journal papers for publication in peer-reviewed international journals. This will make scientific impact from the grant received from IPNI.
· The Nutrient Manager software will be disseminated to large number of farmers in the ACIAR rice-maize project sites where the pot and field studies proposed in this concept note will be conducted. It is expected that many farmers will use Nutrient Manager for rice and maize and thus they will follow the new recommendations and make profits from rice-maize and rice-potato-maize systems. This will make community, social, and economic impacts from the grant received from IPNI.