M Malakouti, M Babaakbari, S Nezami,
Volume 13, Issue 49 (10-2009)
Abstract
To increase grain yield, nitrogen use efficiency (NUE) and nitrogen apparent recovery fraction (NARF) in wheat (Triticum aestivum L.), an experiment was carried out in Karaj Soil and Water Research Station farm for two consecutive growing seasons in 2004-05 and 2005-06. The experimental design was RCBD with 6 treatments (T1= Control T2= 150 kg ha-1 of N as urea in 3-split applications T3= 1/3 N as SCU as the base fertilizer + 2-split urea applications T4= 150 kg ha-1 N as SCU as the base fertilizer T5=150 kg ha-1 of N as urea in 2-split applications and T6=1/3 N as complete fertilizer as the base fertilizer +2-split urea applications) in the first year and 7 treatments (T1= Control T2= 180 kg ha-1 of N as urea in 2-split applications T3= 180 kg ha-1 of N as urea in 3-split applications T4= 180 kg ha-1 N in 5-split urea applications T5 = pre-plant urea + 4-split urea applications T6= 1/3 N as SCU as the base fertilizer +4-split urea applications and T6=1/3 N as complete fertilizer as the base fertilizer +4-split urea applications) in the second year with 3 replications. In the second year, N rate was increased from 150 to 180 kg ha-1, adding the existing extra nutrients in complete macro and fertilizers to other treatments and N split-application was increased up to four times. After harvesting, grain yield, NUE and NARF were measured. The results of first year revealed that the yield, NUE and NARF for T2 (5145 kg ha-1, 13.8 kg kg-1, 41.2%, respectively) and T6 (5067 kg ha-1, 13.2 kg kg-1, 38.2.2%, respectively) were increased significantly at 1% level. In the second year, the maximum grain yield (6335 kg ha-1), NUE (16.2 kg kg-1) and NARF (50%) were obtained again from T6 treatment. Higher yield, NUE and NARF in the second year were mainly due to higher N rates and more N split applications. The economic returns for these substitutions, even without considering any fertilizer subsidies, the averages turned out to be 14, 8 and 4 in these treatments, respectively. Overall results revealed that the substitution of complete macro and SCU fertilizers with pre-plant urea is advisable in wheat production areas. Therefore, it is recommended that the experiment be further tested and evaluated in some wheat growing provinces.l results.
N Ghanavati, M Malakouti, A Hossein Por,
Volume 13, Issue 49 (10-2009)
Abstract
Correlation between components of Q/I and wheat (Triticum aestivum L.) growth indices was studied in a greenhouse experiment during 2003-04 growing season. Eighty soil samples (0 – 30 cm depth) were collected randomly in farms around the Abyak region, Ghazvin province. Twenty-one samples were then selected based on soil texture and NH4OAC-K. The research included treatments of 21 soils and two potassium (K) levels (0, 100 mg/kg) and was conducted in a factorial manner in a randomized complete block design with three replications for studying correlations between Q/I and treatments. Effect of potassium application on the wheat growth was found to be significant at 5% level. The effect of soil properties on wheat growth was also found to be significant at 1% level. However, the interaction of K and soil was not significant. There were no significant differences among the different equilibrium time intervals. The soil potassium buffering capacity (PBCK) values were strongly correlated with CEC (r =0.996**), clay content (r = 0.921**) and moisture saturation percentage (r = 0.811**). Final equation derived from stepwise regression for prediction of PBCK was as follows: PBCK = 7.419 CEC –19.743 R2adj = 0.782** The equilibrium potassium activity ratios (ARke) were strongly correlated with soluble potassium (r =0.846**), NH4OAC-K (r =0.730**), SP (r = 0/794*), OC (r = -0.477ns) and clay content (r=-0.602*). Similarly, readily exchangeable potassium (ΔK0) was strongly correlated with ammonium acetate extractable potassium (r = 0.871**), soluble potassium (r = 0.778**), saturation percentage (r = 0.551*), organic carbon percentage (r=-0.045ns) and clay content (r=-0.206ns). There was no significant correlation between ΔK0 and ARKe with potassium uptake values by wheat. In contrast, there was a strong correlation between PBCK values and potassium uptake by wheat (r = 0.729**), and relative wheat yield (r = 0.735**). There was no significant correlation between Q/I parameters when KCl and K2SO4 were used, and the soil physicochemical properties. However, Q/I parameters obtained from KCl showed a higher correlation with wheat plant's growth indices.
