Land treatment effects on morphometric characters of Three grass species and economic returns from Reseeding in Kitui district, Kenya

This study was conducted to determine the effects of tractor-ploughing and handclearing as land treatment methods on morphometric characters and aboveground biomass production of Eragrostis superba, Cenchrus ciliaris and Enterepogon macrostachyus. The study also evaluated the returns from range reseeding in eastern Kenyan rangelands of Kitui district. Seed viability was tested under laboratory conditions following standard procedures using petri dishes over a period of 17 days. On-farm field trials involved broadcasting seeds of the grass species in two land treatments; namely, tractorploughing and hand-clearing. Each of the grass seeds were broadcasted randomly in six sub-plots (6 m x 6 m) in both treatments at a density of 100 grams m-2 . Thirtyfive plants were randomly selected per sub-plot and tagged for sampling. Measurements of morphometric characters were taken weekly, whereas aboveground biomass was estimated by harvesting standing grasses in the sub-plots after three months of establishment. Data for economic analyses were generated from the costs of physical inputs used and costs incurred at the time reseeding was done. After 17 days of laboratory observation, C ciliaris had the highest percent germination of 28.4%, whereas E. macrostachyus and E. superba had percent germination of 20.1% and 8.6% respectively. These differences were attributed to the intrinsic properties of the grass seeds such as dormancy and tegumental hardness. To ensure successful reseeding in these ecosystems, it is necessary to determine that grass seeds are viable for rehabilitation. Results obtained showed that land treatment had a significant (p<0.05) effect on morphometric characters of grass species. Seedling mortality was found to be significantly higher in the hand-cleared than in the tractor-ploughed plots. In the tractor-ploughed plots, C ciliaris (10.5%), E. macrostachyus (15.4%) and E. superba (24.8%) demonstrated lower percent seedling mortality than those in the hand-cleared plots. Percent mortality was relatively higher (C ciliaris (20.5%), E. macrostachyus (18.2%) and E. superba (32.4%) in the hand-cleared plots than in the tractor-ploughed plots. Similarly, foliage cover, plant height, leaf and tiller numbers in the tractor-ploughed plots were significantly higher (p<0.05) than those in the hand-cleared plots. This scenario was XII attributed to the opening-up of the soil surface, which might have increased capture of scarce rainfall water by the soil in the tractor-ploughed plots than in the handcleared plots. Aboveground biomass was also significantly higher (p<0.05) in the tractor-ploughed than in the hand-cleared plots at the milky stage of grass development. This ranged from; 3,682.5 kg ha-l to 4,908.5 kg ha-l DM, 2,734.0 kg ha-l to 3,240.0 kg ha-1 DM and 1,899.5 kg ha-l 2,434.5 to kg ha-1 DM for E. macrostachyus, C. ciliaris and E. superba, respectively, in hand-cleared and tractorploughed plots. Higher aboveground biomass in the opened-up plots than in the hard soil surface plots was also attributed to increased capture of scarce water by the soil. Of the three grass species tested, E. macrostachyus presented the best results for ecological rehabilitation for the area while C. ciliaris and E. superba were the medium and least suitable grasses, respectively. An economic analysis demonstrated that investing in range reseeding using the two land treatment methods are both economically viable ventures. Computations based on the internal rate of return and benefit-cost ratio derived from the hypothetical sale of hay revealed that a net annual profit of about 15.4% and 26.4% could be obtained from the hand-cleared and tractor-ploughed investment respectively. This study also demonstrates that reseeding a similar area using these treatment methods can yield a benefit-cost ratio that is greater than one. Furthermore, E. macrostachyus, C. ciliaris and E. superba are all economically feasible species for reseeding in the eastern rangelands of Kenya. It is however recommended that, a study covering more than two seasons be carried out, as this would yield more information on the establishment of pastures under the two land treatment methods. Other potential species such as Digitaria macroblephara, Cynodon dactylon, Chloris roxburghiana and Themeda triandra should also be studied under different land treatment methods so as to increase knowledge on how to capture the scarce water by the soil which may be used to boost forage production and halt degradation in the rangelands. XIII