use of aqua ammonia for the control of soil borne diseases in tomato

The efficacy of aqua ammonia [NH[4]OH, 28% N] for the control of nematodes and Fusarium and Verticillium wilts on tomato was studied in three greenhouse experiments grown in infected soil plots in Lebanon. Aqua ammonia [NH[4]OH] was applied as diluted liquid in furrows and by a drip irrigation system at the rates of 50 [normal N fertilization rate], 75 and 100 mL m[-2] [double N fertilization rate]. Levels of control of aqua ammonia, applied as a single application before planting, were comparable to those of Agrocelhone [soil fumigant, mixture of Dichloropropene 55.4% + Chloropicrin 33.7%] achieved at a rate of 100 ml NH[4]OH m[-2]. Root galling in the control treatment was much higher than the other treatments. The yield and number of hairy roots of the control treatment were very restricted when compared to the NH[4]OH and Agrocelhone treatments.

Potassium status in some lebanese soils

This study was conducted to evaluate K content and availability in Lebanese soils using the traditional methods of K measurement, K-thermodynamics and K-kinetics measurements. Nine surface soil samples [0-30 cm] were collected from major agricultural regions in Lebanon and were later exposed to the following laboratory measurements. Extraction of K with H[2]O, IN NH[4]OAc and IN HNO[3], and calculation of: K-flxation capacity, ionic strength, K-activity ratio, free energy of replacement [- delta F], Q/I relationship. Five K-kinetic equations were compared by applying the least square regression analysis to determine the suitable ones for describing K release from soils. The results showed that the tested soil samples varied widely in K contents and K supplying power to plants. According to NH[4]OAc and HNO[3] extraction methods, the K levels of samples 5 is high, 7 is medium, 9 is medium/low and the other 6 samples are low. The values of H[2]O-K didn 't follow the same order. The values of KSP were low in all samples except 5 and 6. The amounts of fixed K in the studied samples varied from 1.53 Cmol.Kg[-1] to 5.02 Cmol.Kg[-1]. The activity ratio values ranged between 0.0008 and 0.018. The values of free energy of replacement [- delta F] showed that soils 5 and 6 have medium K supplying power. The values of K-buffering capacity ranged between 22.0 Cmol.Kg[-1]/mol/L and 297.8 Cmol.Kg[-1]/mol/L. The values of labile K were lower than those of available K. This means that a part of exchangeable K exists on sites with high bonding energy. The release capacity ranged between 9.5% and 59.1%. From the five mathematical models which were tested, the first order equation was the most suitable and was selected to determine the release rate coefficient of K. The results show that K content in Lebanese soils differs widely and the results of soil testing should be compared to field responses