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Abstract
The productivity of amaranthus (Amarantus cruentus) can be increased by using organic fertilizer in combination with good agronomic practices. The significance of this strategy was tested in pot and field at Ladoke Akintola University of Technology, Ogbomoso, Nigeria in 2003. Three cutting heights (10, 15 and 20 cm); three rates (2, 4 and 6 t / ha) of crop residue compost and non -fertilized plants and those that were not cut constituted the treatments. The treatments were replicated thrice and laid out in a randomized complete block design. Growth parameters such as plant height, girth, number of leaf /plant and leaf area were assessed at first cutting (four weeks after sowing) while dry matter, shoot yield and shoot N, P and K uptake were determined at each cutting interval. The cumulative dry matter yield, shoot yield and N, P and K uptakes respectively were obtained by adding their values obtained at different harvest time.
Plant grown with 4 t ha –1compost had significantly taller plants, stem girth, leaf area, leaf number per plant as well as higher dry matter shoot yield and tissue, P and K concentration. Generally, the results of the pot and field trials were similar, however field grown plants performed better than pot grown ones. Cutting height significantly influenced the dry matter, shoot yield and shoot N, P and K uptake. Cutting of plants at 20 cm above soil level led to a higher accumulation of dry mater. The highest reduction in shoot yield and NPK uptake came from the 10 cm cutting height and this became more marked at low compost rates. In the pot trial the shoot yield of 10, 15 and 20 cm cutting heights were 7. 3, 7. 4 and 8. 2 t ha –1 respectively. The shoot yield of non – cut plants (17.3 t ha-1) was similar to that got from plants cut at 20 cm. Results revealed that repeated cutting of amaranthus re – growth improved its productivity and that the higher the amount of nutrients in the soil for plant uptake the greater the advantage. It is apparent that, cutting amaranthus at 20 cm above soil surface in combination with 4 t compost ha –1 could be good agronomic practices for optimum performance of the crop.
Keywords: Cutting height, compost, Amaranthus, Dry matter shoot yield, Nutrient uptake.,