Victor Rotich Kipkoech2024-07-102019-10ROTICH, V. K. (2019). ROTATIONAL EFFECTS OF GRAIN AMARANTH (Amaranthus hypochondriacus L.), SOYBEAN (Glycine max L.) AND NITROGEN ON STRIGA HERMONTHICAINFESTATION AND MAIZE (Zea maysL.) PERFORMANCE IN SIAYA COUNTY (Doctoral dissertation, University of Eldoret).https://repository.nrf.go.ke/handle/123456789/1226ThesisMaize is a dominant food crop in Kenya. It is a crop consumed in various forms by both urban and rural population and thus important in terms of food security. It is also grown for use as livestock feeds. Maize production in Siaya County is decliningdue to Striga weed infestation, soils degradation, pest infestation and unreliable rainfall.The aim of this study wasto determinetherotational effects of grain amaranth, soybean and nitrogen fertilization on Striga hermonthicainfestation and maizeperformancein Striga infested soils. On-farmtrials were conducted from August 2014 to July2015at Ugunja, Siaya county, western Kenya.The treatments included grain amaranth, soybean, maize and nitrogen. Grain yields and economic productivity of each crop was also determined. The maize test crop whichwas supplied with five levels of nitrogen, 0, 50, 100, 150 and 200 kgNha-1. Fifteen treatments were arranged as a split-plotin a randomized complete block design (RCBD) replicated three times. The main plot consisted of grain amaranth, soybean and maize while the subplotsconsisted of nitrogen rates. Maizewithout N fertilizersucceedingsoybeanresulted to 41.2% reduction on Strigacount while maize withoutN fertilizersucceeding amaranthresulted in 34.4% reduction on Strigaat 12WAP as compared to that producedfrom maize without N fertilizer succeeding maize in the rotation. The highest Striganumber (31.44/m2) at 12WAP was observed on maize mono-cropsystem withoutN fertilizer whilethe lowest Striga numbers (6.89/m2) at 12WAPwas observed on soy bean-maize crop rotation system. Thoughlower than soybean-maize rotation, amaranth-maize crop rotation at all level of N resulted inhigher maize yield than in maize-maize crop rotation at similar levels of Nitrogen. Grain amaranth-maize rotation system interacting with 200kgNha-1resulted in 10.5% maize yield increase while soybean-maizerotation system interacting with 200kg N ha-1resulted in 25.7% increase in maize yield as compared to maize-maize crop rotation system interacting with 200kgNha-1. Similarly, there was a significant increase in maize height and stover yield in grain amaranth-maizecrop rotation system, soy bean-maize crop rotation system at all levels of N than in maize-maize crop rotation. The study showed that crop rotation involving grain amaranth-maize and soybean –maize resulted in lower Striga population and higher returns of maize than maize-maize crop rotation system and hencethis study recommend the adoption of amaranth-maize crop rotation system and soybean –maize crop rotation system by farmers as an efficient cropping system, strategy to reduce Striga,increase maize yield and improve nutrition of people in rural and urbanenAmaranth rotational effectssoybean rotational effectsmaize rotational effectsnitrogen rotational effectsThesis