In the tropics, the water potential of a region cannot be adequately assessed from precipitation alone due to the seasonal character of rainfall and even more so owing to the changing climate scenario. It is therefore necessary that in any agro-climatological program, there must be a clear understanding of the actual amount of water that evaporates and transpires (AET), and the amount of water that would evaporate and transpire if water were always readily available (PET). This could be done through the method of the water balance. The present work examines the water budget of parts of the Imo river basin and its implications for improved crop production through supplementary irrigation schedules. It was observed, that the study area is already facing moisture-stress. This is because even during rainy months supplementary irrigation is required to compensate for the occasionally moisture deficit due to increased evapotranspiration. The study showed that cultivation of maize, rice and tomatoes can be carried out on an all-year round basis under a scientific irrigation scheme. Thus the study provided farmers with guideline on the period and quantity of water required for supplementary irrigation, a development which will prevents wilting of plants before the application of needed water.

Most of the world irrigation systems were developed on a step-by-step basis, over the centuries, and were designed for a long life (50 years or more), on the assumption that climatic conditions would not change in the future. This will not be so in the years to come due to the global warming and greenhouse effect. Therefore, engineers and decision makers need to systematically review planning principles, design criteria, operating rules, contingency plans and management policies for new infrastructures. In relation to these issues and based on available information, the report gives an overview of current and future (time horizon 2025) irrigation development around the world. Moreover, the paper analyses the results of the most recent and advanced General Circulation Models for assessing the hydrological impacts of climate variability on crop requirements, water availability, food security and the planning and design process of irrigation systems. Finally, a five-step planning and design procedure is proposed able to integrate, within the development process, the hydrological consequences of climate change | [A livello mondiale, la maggior parte dei sistemi di irrigazione è stata sviluppata gradualmente, nel corso dei secoli ed è stata progettata per lunghi periodi (50 anni o più) in base al presupposto che le condizioni climatiche non sarebbero cambiate in futuro. Questo non sarà più vero per i prossimi anni, per effetto del riscaldamento globale e dell'effetto serra. Perciò, i tecnici e i politici devono rivedere sistematicamente i principi di programmazione, i criteri di progettazione, le norme operative, i pianti di emergenza e le politiche di gestione per le nuove infrastrutture. In relazione a queste questioni e in base alle informazioni disponibili, il contributo fornisce una panoramica dello sviluppo presente e futuro (orizzonte temporale al 2025) dello sviluppo dell'irrigazione a livello mondiale. Inoltre, il lavoro analizza i risultati dei Modelli di Circolazione Generale più recenti e avanzati per determinare gli impatti idrologici della variabilità climatica sulle esigenze delle coltivazioni, la disponibilità di acqua, la sicurezza alimentare e il processo di programmazione e progettazione dei sistemi di irrigazione. Infine, viene proposta una procedura di programmazione e progettazione a cinque fasi, in grado di incorporare nel processo di sviluppo le conseguenze idrologiche del cambiamento climatico]

This report covers the first visit by the NRI team to Ghana in the start-up of the agronomy component of the Integrated Food Crops Systems Project (IFCSP). The team was fully supported by in-country IFCSP personnel, VSO (Ms Meijer) and other collaborators. The purpose of the visit was to establish the project on the ground following funding approval from the NRSP FAI programme. This involved defining the activities of the various collaborators and conducting a participatory rural appraisal of farmers' perceptions and practices for maintaining soil fertility in dry season vegetable producing areas of Brong Ahafo region. The PRA which was carried out in four typical vegetable growing areas revealed that farmers use considerable amounts of inorganic fertilisers but are concerned about their costs and that increased quantities are required to maintain yields at former levels. Many farmers practice fallowing to maintain soil fertility and to avoid pest build-up, but generally fallow periods are becoming shorter. The project aims to overcome these constraints through the introduction and testing of suitable legume cover crops and green manures. A strategy for introducing the concept of cover crop and green manure usage and testing was developed for each of the four study locales following completion of the PRA. Strategies are related to the soil type(s) present, water availability and husbandry practices employed. Arrangements were made with SRI to conduct an initial soil survey and analysis of two surveyed areas before the start of the rains in April. Funding for the survey will be provided from the newly opened project account in Sunyani. Arrangements were made to purchase seed of suitable cover crops from CRI and seeds of those not available were ordered from European suppliers. Agreement for importing new accessions were made with the Plant Protection and Regulatory Services Department (Accra) and the Plant Genetic Resources Centre, at Bunso.