1 The growth response of coffee plants to organic manure, inorganic fertilizers and integrated soil fertility management under different irrigation levels A. Chemura a , C. Mahoya a , D. Kutywayo b and P. Chidoko a a Department of Research and Specialist Services, Coffee Research Institute, P.O.Box 61, Chipinge, Zimbabwe b Department of Research and Specialist Services, Agricultural Research Centre, P.O.Box CY594 Causeway, Harare, Zimbabwe Abstract A study was carried out to determine effects of organic, inorganic fertilizers and integrated soil fertility management and irrigation levels (1000ml, 750ml and 500ml per planting station) on coffee growth. There were no significant differences (p>0.05) in girth, leaves and primaries due to the different soil fertility management options. Significant differences (p<0.05) due to soil nutrient sources were observed in coffee height where inorganic fertilizer treatment resulted in tallest coffee plants (47.4cm) and integrated soil fertility having the shortest coffee trees (42.8cm) after one year. The highest irrigation level of 1000ml had the tallest plants with thickest stems while the lowest level had the shortest and thinnest plants (p<0.05). No significant differences were observed in number of leaves and primaries due to irrigation treatments. Results indicate that inorganic fertilizers are most effective at high irrigation levels while organic manure perform better than inorganic fertilizers under low irrigation water levels. 1 INTRODUCTION Soil fertility management and water supply are important for successful crop production in all agricultural commodities. The use of inorganic fertilizers has been a significant contributor to increased crop productivity since the green revolution, and has resulted in reduced use of organic nutrient sources that farmers have relied on for centuries (1). The quality of fertilizers, their costs and yield contribution are as variable as their sources. The most common sources of organic manure used in crop production are livestock dung, composted and green crop residues, farmyard matter and organic manure from natural systems and material production systems (1; 2). The need for renewable, locally available and cheaper options for supplying nutrient to crops is increasingly becoming important because of the need for sustainable agriculture (3-5). With growing demands for sustainably produced agricultural produce for environmental, social and food safety reasons, the use and recycling of organic matter is becoming inevitable, particularly for export market depended commodities such as coffee. Sustainable agriculture is a production process and farm management system that has positive economic, ecological and social benefits in the short and long term (6). The levels of sustainability varies on a sliding scale from the strict organic farming methods that demand perfect quality of the production process and the environment to general guidelines and codes of conduct on various aspects of the expectations of the production system (6; 7). Use of organic soil fertility options is among the key attributes of sustainable agriculture. Maintaining physical, chemical and biological soil properties for plant growth and environmental efficiency requires the input of organic matter that is decomposed into nutrients and used up by plants. Sustainable production is becoming a necessity for coffee sectors to remain competitive in the global trade against oversupply and price fluctuations that in some years result in coffee price crisis. Reliance on inorganic fertilizers may not be sustainable in the long term given that soils may lose microorganisms, become acidic and having unstable aggregates leading to erosion and general degradation, and this may explain yield decline with time despite consistent use of inorganic fertilizers (5). Studies on the potential of using organic nutrient sources in coffee production identified cattle manure as the most promising (2; 8; 9) while recycling coffee wastes such as pulp and prunings as direct inputs or in combination with green manures and live mulch in nutrient management were effective in promoting coffee growth and yield and also economically viable (10). On the other hand, some studies have shown that organic manures are very important for maintaining soil organic matter and supplying nutrients to the coffee systems but may not be enough for balanced plant nutrient flows and for achieving profitable yield levels (11). This is because the maximum N obtainable from common organic manures is less than 10%, P less than 2% and K and less than 10% of dry matter compared with high nutrient outflows of up to