The researches were carried out during 2007-2009 in the Agricultural Research and Development Station Oradea on the preluvosol characterized by the presence of the horizons Bt1 (34-54 cm depth) and Bt2 (54-78 cm depth); the colloid clay eluviation determined to appear the El horizon with 31.6% colloid clay. On 0-20 cm depth, the soil has a big percentage of macroagregates (Φ > 0.25 mm), 47.5% bulk density is of 1.41 g/cm3 and total porosity is median one, hydraulic conductivity is of 21.0 mm/h. The values of the pH indicates a low acid soil, humus, total nitrogen, phosphorus and potassium content are low. The source of irrigation water was a drill of 15 m depth. The chemical parameters of the irrigation water were the following: fixed mineral residue 0.5 g/l; SAR index 0.52; CSR index= -1.7%; N. Florea class = II; there are not some problemes regarding the use of irrigation use.Ten to ten day determination of the soil moisture emphasized the decrease of the soil water reserve on watering depth (0-100 cm) bellow easily available water content every yea, and the irrigation was needed for optimum water provisionment. The use of the irrigation for maintaining the soil water reserve between easily available water content and filed capacity determined the improve of the water/temperature + light report, the increase of the daily  water consumption and of the total consumption and the yield gains very significant every year; the water use efficiency was (kg/m3) was improved with 18. 7 %. The researches are part of the project” Study of the relationships in the soil-water-plant-atmosphere system on the land affected succesivelly by excess and deficit of moisture from North Western Romania regarding the improve of the yield quantity and quality”PN-II-ID-PCE-2008-2; 1103/2009.The presence of the pedological drought every year and the improves determined by irrigation-microclimate conditions, water consumption, yield gains, water use efficiency- are the arguments for irrigation use in alfalfa 2nd year in the Crisurilor Plains.

pedological drought; irrigation; yield gain; alfalfa

Presentation: oral