Effect of Irrigation Water Amounts and Nitrogen Rates on Optimum Maize Yield and Net Return Under Drip Irrigation Systum at Northwest Delta, Egypt

Abstract

Two field experiments were carried out at Wady Elnatron, El-Behera Governorate, "Wady Elnatron located in the west desert near the Delta about 90 kilometers north west of Cairo", during 2008 and 2009 seasons to study the effect of irrigation water amounts and nitrogen rates on maize yield and the net return from these treatments under drip irrigation system. Split plot design was used with four replicates. The main plots were assigned by four irrigation water amounts (100 %, 90 %, 80 % and 70 %) of evapotranspiration (ETc). The sub-plots were randomly assigned by four nitrogen rates (zero, 50, 100 and 150 kg N fed.-1 ) as ammonium nitrate (ha = 2.4 fed.). The other recommended agriculture practices were done. Four polynomial quadratic equations were established to show the following results: 1. The maximum and optimum N rates (Xm and Xopt) were increased by decreasing irrigation water amounts from 100% to 70% of ETc in the two seasons. 2. The maximum and optimum maize yields (Ym and Yopt) were decreased by decreasing irrigation water amounts from 100% to 70% of ETc in the two seasons. 3. The highest maximum yield (4.307 ton fed.-1 ), the highest total value of yield (6394.5 L.E fed.-1 ) and the highest return of N fertilizer (1744.5 LE fed.-1 ) were obtained with 100 % of ETc used in the two seasons. 4. The efficiencies of N rates (eX) were decreased by increasing N rates from N0 to N1, N2 and N3, respectively with different irrigation water amounts. 5. The relative efficiency (EX), the efficiency of nitrogen fertilizer at optimum rate (eXopt) and the efficiency of soil nitrogen (eXs) were decreased as irrigation water amounts decreased. 6. The soil nitrogen content during plant growth (Xs) was decreased as irrigation water amounts decreased. 7. The contribution of soil N was decreased as irrigation water amounts decreased in the two seasons. 8. The contribution of N fertilizer was increased by increasing N levels in the two seasons.

Response of Some Wheat Varieties to Nitrogen Fertilization

“…With regard to  % values, increasing N levels from N 0 to N 30 increased grain yield by 75.2% while it was only increased by 25.5% and 6.7% when N level increased to N 60, and N 90 respectively, showing that yield increase declined by increasing N level. Many investigators such as Hassanein and El-Shebiny (2000), Mashali et al (2011) and Atia et al (2012) stated that the highest increase of yield and highest efficiency of nitrogen fertilizer was at the first dose and decreased as N levels increased. These results are in agreement with those reported by El-Zaher and Salem (2005), Abdelgader et al 2010and Knany et al (2011).…”

“…Thabet and Balba (1994), Hassanein and El-Shebiny (2000), Atia (2005), Atia et al. (2009), Mashali et al (2011) and Atia et al (2012) calculate the net return of nitrogen applied to decrease the costs of added fertilizers at the minimum point.…”