Effect of Water Quality and Weeding on Yield and Quality of Three Alfalfa (Medicago Sativa L.) Cultivars (Report‪)‬

Introduction The estimated number of livestock in Sudan is 165 millions heads, which is equivalent to about 86 million animal units (AOAD, 2001). The feed balance for livestock is negative because of desertification and degradation of range vegetation. The current gap in livestock feed was estimated at 104.4 million tons, which represent almost 50% of the total requirement of livestock feed (Abusuwar and Darag, 2002). To cope with the increase in animal resources and the shortage in forage produced in natural rangelands, expansion and improvement of irrigated forages become a necessity. Alfalfa (Medicago sative L.) is the most important forage crop grown in the Sudan. The total area cultivated by the crop is about 52,500 ha, the annual production is estimated at 1,002,500 tons green forage and the crop contributes about 94% of the total irrigated forages in the country (Abusuwar, 2004). The crop is exclusively grown under irrigation, particularly along the Nile from Khartoum State northwards. It is left to grow for 2-4 years giving a cut every three weeks on average. At the end of the third to fourth year, the crop may be left to produce seeds during the hot dry period, from March to May (Nayel and Khidir, 1995). The most serious problem in alfalfa production in the Sudan is the sharp decrease in forage yield during the Damira season (the period when River Nile floods). This may continue for 3-4 months, and is accompanied by severe weed infestation. High weed infestation, especially during Damira time, is thought to be due to the fact that river water transports weed seeds to fields through irrigation. Use of selective herbicides to control weeds is beyond the financial capacity of farmers, as they are expensive they can not afford it. Consequently looking into an alternative to control weeds becomes a necessity. Moreover, the dependence on one local variety (Hegazi) without improvement or introducing exotic cultivars is part of the feed gap problem. The Hegazi cultivar has been grown in the Sudan for more than 90 years (Agabawi, 1968) without any serious efforts to improve it. During the eighties some of the exotic cultivars brought from the USA and Australia were tried with promising results (Abusuwar, 2004).