**Author details**

**4.2. Suggestion for indigenous organic material application in Ashanti region, under**

Similar to what was observed in Northern region, the use of RS is considered as an effective resource for rice production in Ashanti region, because of its high accessibility. However, unlike the Northern region, RW-RS in Ashanti region showed a smaller effect on rice pro‐ duction than the other treatments. Most rice fields in Ashanti region are irrigated and can be used to cultivate throughout the year. Therefore, rice fields are generally maintained under submerged condition for long periods hence decomposition rate of organic matter will be relatively slow. Hence, RW-RS application is discouraged because its effect on rice yield is

Poultry manure with every pretreatment showed high positive effect on rice yield enhance‐ ment, especially in CO-PM. Poultry manure is a popular organic material that is an effective

In the SD treatment, RW-SD showed lower value (5.47 t ha-1) than WOM of rice yield (5.52 t ha-1). Similar to RW-RS, direct application of SD generally has the problem due to its high C/N ratio. Moreover SD composting is also difficult because SD consist of woody material that contains resistant organic matter. To avoid plant damage by organic acids and/or nitrogen starvation, SD composting needs to take a long time for decomposition and fermentation. Combustion treatment, which take shorter time and is easy to practice (CH and ASH) is affordable and effective for agricultural usage in Ashanti region. The possibility of composting through inoculation with microorganisms should not be exclud‐

In the organic material application in Ashanti region, all treatment except direct application of RS and SD showed positive effect on rice grain yield. It is suggested that ASH-RS, CH-RS, ASH-SD, CH-SD, and composting RS or SD combined with PM, and also RW-PM, are evalu‐ ated as promising technical options that are accessible and effective for rice cultivation in Ashanti region. These selected options showed relatively high value not only in rice yield but also in agronomic efficiency of BPR application. The effect of organic material applica‐ tion on enhancement of PR solubility was smaller compared with the effect observed in Northern region. However, direct application of PR in this region indicated high agronom‐ ical efficiency to TSP application, and means PR has possibility of alternative usage against TSP. Further investigation need to be conducted on the effect of RP combined with organic

This investigation was conducted under the project "Improvement of Soil Fertility with Use of Indigenous Resources in Rice Systems of Sub-Sahara Africa', which was funded by the Ministry of Agriculture, Forestry and Fisheries (MAFF), Japan. The authors are grateful to the entire staff of CSIR-SRI, UDS both in Ghana and JIRCAS for their technical supports.

**water controlled lowland rice cultivation in Equatorial forest zone**

not pronounced, and a possible risk of nitrogen starvation.

P source, and that is highly accessible in the Ashanti region.

ed from future investigation.

42 Soil Fertility

material application on rice yield.

**Acknowledgement**

Satoshi Nakamura1 , Roland Nuhu Issaka2 , Israel K. Dzomeku3 , Monrawee Fukuda1 , Mohammed Moro Buri2 , Vincent Kodjo Avornyo3 , Eric Owusu Adjei2 , Joseph A. Awuni3 and Satoshi Tobita1

1 Japan International Research Center for Agricultural Sciences (JIRCAS), Ohwashi, Tsukuba, Ibaraki, Japan

2 CSIR-Soil Research Institute (SRI), Academy Post Office, Kwadaso - Kumasi, Ghana

3 University for Development Studies (UDS) Faculty of Agriculture, Department of Agronomy, Tamale, Ghana
