Showing 2 results for Ph.
A. Ronaghi, M. R. Chakerolhosseini, N. Karimian,
Volume 6, Issue 2 (7-2002)
Abstract
Phosphorus (P) and iron (Fe) are essential nutrients for plants. Iron availability is low in calcareous soils of Iran due to the excessive amounts of CaCO3 and high pH. Overfertilization of P fertilizers may also decrease Fe availability. The objective of this study was to evaluate the effect of P and Fe on the growth and chemical composition of corn (Zea mays L.) under greenhouse conditions. Treatments consisted of a factorial arrangement of P rates (0, 40, 80, 120 and 160 mg kg-1 as KH2PO4) and Fe rates (0, 2.5, 5 and 10 mg kg-1 as Fe EDDHA) in a completely randomized design with four replications. Plants were grown for 8 weeks in a loamy soil, calssified as Chitgar series (fine-loamy, carbonatic, thermic, Typic Calcixerepts). Results showd that P application up to 80 mg kg-1 increased corn top dry matter. Corn P concentration and total uptake increased by P application but decreased by Fe application. Application of Fe up to 5 mg kg-1 increased dry matter but decreased it at higher rates. Concentration and total uptake of Fe increased by Fe application but decreased by P application. Zinc and copper concentrations decresed significantly when P was added. Manganese concentration increased at 40 mg P kg-1 but decreased at higher rates. Iron application decreased zinc and manganese concentrations but had no effect on copper.
M. A. Mohammadi, M. Zarea Khormizi, A. Kavian,
Volume 19, Issue 72 (8-2015)
Abstract
Sediment yield of watersheds results from different erosional and hydrological processes which make it too complicated to be predicted. Awareness of runoff and sediment yield regimes is useful to better understand the erosional condition of watersheds for management. Therefore, determination of factors controlling hydro-sedimentary response of watersheds is very necessary. For this purpose, ground surveying and measurements of hydrograph and sediment graph were carried out in the representative basin of Khamsan in the uplands of Gavshan dam during 9 months. Finally, relationships between runoff and sediment yield were obtained, then corresponding runoff-sediment events were analyzed. Results showed that 5 events out of 6 occurring runoff events had eight-shaped hysteresis loop and only one event showed clock-wise hysteresis loop. Among them, the highest and lowest flood discharges were attributed to the events of 02.11.2010 and 05.01.2011 with 151488 M3 and 11764.8 M3 Run off, respectively. The study also showed that for this watershed no specific type of loop existed for a particular season. Accordingly, the seasonal patterns could not be attributed to a particular type of loop. Precipitation and runoff characteristics may have also played a role in addition to other factors. Results emphasize the importance of rainfall distribution and rising-falling limbs of hydrograph for the corresponding hysteresis loops in small watersheds.
