EFFECT OF COMPOSTED PARTHENIUM BIOMASS, MINERAL NP FERTILIZERS AND WEEDING FREQUENCY ON BARLEY PRODUCTION IN TIGRAY REGIONAL STATE, NORTHERN ETHIOPIA

two pot and one field experiments were conducted in 2013 and 2014 to determine mineral nutrition of parthenium compost and fresh residue by different composting techniques and application methods in combination with NP fertilizers. The experiment on effect of parthenium compost types and NP fertilizer on growth, yield attributes and yield of barley comprised three types of parthenium composts [normal, effective microorganism (EM) enriched and vermicompost] each at 2.5 and 5.0 t ha-1 and control were combined with NP fertilizer (0, 50, and 100%) of the recommendation for barley. The results showed that vermicomposted parthenium 5 t ha-1 at 50% and 100% NP combinations prolonged heading by 12 days and maturity by 18. More number (2.7) of productive tillers, kernels per plant (7) and thousand kernel weight (8 g) were recorded in response to the combination of vermicompost 5 t ha-1 and 100% recommended NP. Grain and above ground biomass yields increased due to combined application of parthenium vermicompost at 5.0 t ha-1 and 100% recommended NP by 65 and 53.3%, respectively. The experiment conducted to investigate the effect of parthenium fresh residue in combination with NP fertilizer included two types of parthenium fresh residue (soil incorporated and surface applied) each at two rates (2.5 and 5.0 t ha-1) and control; combined with 0, 50 and 100% recommended NP rate for barley. Crop emergence was delayed by two days for surface applied parthenium residue of 5 t ha-1. Early heading by 10 days was recorded at a combined application of surface applied 5 t ha-1 parthenium residue and 50% of recommended NP. Soil incorporated residue at 2.5 and 5 t ha-1 resulted in four more days to maturity of barley than the surface applied residue. Significantly taller plants were recorded for the soil incorporated and control treatment than the surface applied residue. Highest number of kernels per spike (22) obtained was at the combination of soil incorporated parthenium residue at 5 t ha-1 and 100% the recommended NP. Yield increase for soil incorporated parthenium fresh residue at 5 t ha-1 was 30% over the control and 36% over surface applied residue at 5 t ha-1. The significance of these xvi findings is that parthenium weed could be sustainably managed through soil incorporated fresh residue application in the infested farm lands. The field experiment with parthenium compost types, fresh parthenium residues and weeding frequency comprised a factorial combination of three types of parthenium composts [normal, EM enriched and vermicompost], fresh parthenium residue each at the rate of 5.0 t ha-1, recommended NP for barley, and control. All these treatments were combined with three weeding frequencies [no weeding, one hand weeding and hoeing at three weeks after crop emergence (WAE) and two hand weeding and hoeing at three and six WAE]. Broad-leaved weed species were dominant at both sites with relative density of 57 and 80% at research station and farmers field, respectively. Low weed density was recorded at the no compost and fresh residue treatment for both sites and high weed density at the recommended NP and vermicompost treatments. The lowest weed dry weight was recorded at the no compost and fresh residue treatment and higher dry weight at fresh residue across all weeding frequencies. Vermicomposted pathenium delayed heading and maturity of barley by five and seven days, respectively. Significantly taller plants (75.5 cm) were in the 100% recommended NP which was statistically at par with vermicomposted parthenium, while the shortest plants (63.83 cm) were in the control treatment. Significantly higher number of productive tiller m-2 (170), kernels per spike (31) and thousand kernels weight (34) were recorded for the vermicomposted parthenium 5 t ha-,1 which was at par with the recommended 100% NP, and two hand weeding and hoeing. The combination of recommended NP at two hand weeding gave the highest grain yield (3000 kg ha-1). However, the economic analysis revealed that the highest net benefit of ETB 25655.3 ha-1 was obtained in response to the combination of vermicomposted parthenium at two hand weedings. In conclusion, vermicomposted parthenium at 5 t ha-1and two hand weedings can be used for a successful management of the weed and its long term effect in improving soil organic matter.