AGRO-ECOLOGICAL ZONING OF IRISH POTATO BASED ON WATER REQUIREMENTS AND CLIMATE VARIABILITY IN THE RWANDAN HIGHLANDS (A case of Congo-Nile ridge)

The area of study is located in the Northern and western Provinces touching the following districts: Musanze, Nyabihu, and Ngororero. Rwanda Being a country with an economy essentially based on rain-fed agriculture, it is with no doubt vulnerable to negative effects of climate change, its adaptive capacity to impacts related to extreme meteorological phenomena is very low (MINITERE, 2006). The above-mentioned reasons have given us the occasion to conduct our research focusing on “agro ecological zoning of Irish potato based on water requirement and climate variability in the Rwandan highlands”. To get results we have put forwards the following hypotheses:

    Identification of current situation of Irish potato determines its productivity;

    The climate changes are the main causes of low Irish potato’s Production;

    The adequate soil management, ensure sufficient Irish production;

    Local farmer’s organizations give their deep contribution to reach maximum production of Irish potato.

The method followed was to make the interview with the opinion farmers, the field visits was carried out to take the GPS data; the results were arranged in two ways: questionnaire analysis and CROPWAT computations. The results show that potato is cultivated at a large extent 2.52 rank. Most farmers grown their potato on hillsides (78.8%) with the results indicated that February and May are adequate periods (months) to cultivate potato (as both represent 36.5 % each one), while harvesting in June and September represented by 25%, and 23.1% respectively. There are some parts were they grow potato three times a year (Season C) the area is cold (71.3%) and the rainfall is high. The higher yield was observed in Bigogwe sector (275kg/are). Altitude significantly influenced rainfall and relative humidity in the Congo Nile Ridge. Using statistical analysis of critical climatic parameters and cropwat simulation leads to following statement:

    Potatoes cannot be equally grown in the CNR;

    Some area in CNR may grow potatoes 3 times a year other only twice.