Influence of Organic and Conventional Farming Practices on Weeds In Murang’a and Tharaka-Nithi Counties, Kenya
| dc.contributor.author | Maina, Obadiah Mwangi | |
| dc.date.accessioned | 2025-07-01T09:08:34Z | |
| dc.date.available | 2025-07-01T09:08:34Z | |
| dc.date.issued | 2024-03 | |
| dc.description | A Research Thesis Submitted in Partial Fulfillment of the Requirement for the Degree of Master of Environmental Science (Environmental Science) in the School of Agriculture and Environmental Sciences of Kenyatta University, March 2024 Supervisors: 1. Monicah Mucheru-Muna 2. Hottensiah Wambui Mwangi | |
| dc.description.abstract | Developing nations along the equator are facing problems with amplified food requirements due to rapid population growth. Population in African is estimated to be 2.5 billion by 2050. Despite 60% of its population engaging in agriculture, production of sufficient food is still a problem as a result of deprived soil nutrient, low seed quality, infestation by pests and diseases and poor weed management practices. The goals of the research were to; i) evaluate the influence of varying N and P fertilizer application rates on weed density and diversity in conventional and organic farming systems, ii) identify species of weeds that dominate in conventional and organic farming systems and, iii) assess how weed density, dominance, and diversity are influenced by crop rotation in conventional and organic farming systems. To address these objectives, soil samples were taken between July 2017 and December 2019 in long term trial established since 2007. Trials were set in a randomized complete block design comparing conventional and organic farming at high and low inputs in Thika and Chuka sites in Kenya. For high inputs, 225kg N ha-1and 125kg P ha-1were used, and for low inputs 45kg N ha-1 and 26kg P ha-1 were used in six-cropping season. The influence of farming systems on weeds was determined in a greenhouse experiment using soil samples taken. Weed seedling emergency method was used for weed data collection. The samples were sieved using a 3mm sieve and treated with gibberellic acid to break weed seeds dormancy then placed in germination trays and placed randomly inside the greenhouse. Watering was done at moderate soil moisture to ensure weed seeds germinate. Germinated weed seedlings were counted and their species identified. The data obtained were analyzed using analysis of variance on GenStat 14th edition and means separated using least significant difference (P≤0.05). The outcomes indicated that farm inputs, cropping sequence and weed management practice were the key factors significantly (P≤0.05) influencing weed density, dominance and diversity. Chuka and Thika recorded 13 and 12 weed species, respectively. Fertilizer application rates of 225kgNha-1 and 125kgPha-1 resulted to a significant (P<0.05) high density of Bidens pilosa, Amaranthus hybridus, Stellaria media and Galinsoga parviflora. In the two trial sites, organic high resulted to a significant (P<0.05) high weed density. Dominant weed species were Bidens pilosa (17.8%), Galinsoga parviflora (17.7%), Schkuhria pinnata (13.9%) and Setaria verticillate (13.1%) in Chuka and Stellaria media (23.5%), Bidens pilosa (23%), Eleusine indica (20%), and Amaranthus hybridus (11.9%) in Thika. Their densities were reduced under the 3-years crop rotation. Maize-cabbage rotation decreased weed density except for Eleusine indica and Sonchus oleraceus while maize-beans rotation increased density of Eleusine indica. Shannon diversity (H’) index was high in organic farming. Shannon evenness ratio in Thika and Chuka for organic high to conventional high and organic low to conventional low were (2:1 and 2:1.4), and (2:1.8 and 2:1.6), respectively. From the study result, fertility input leads to increase in weed density while integration of intercrop in a crop rotation, helped in controlling weed density. | |
| dc.description.sponsorship | Kenyatta University | |
| dc.identifier.uri | https://ir-library.ku.ac.ke/handle/123456789/30249 | |
| dc.language.iso | en | |
| dc.publisher | Kenyatta University | |
| dc.title | Influence of Organic and Conventional Farming Practices on Weeds In Murang’a and Tharaka-Nithi Counties, Kenya | |
| dc.type | Thesis |