Determination of Rhizobitoxine and Dihydrorhizobitoxine in Soybean Plants by Amino Acid Analyzer

Investigations were carried out on the effect of the activity ratio of potassium to calcium and magnesium in the nutrient solution applied by drip irrigation on the growth and nutrient uptake of lettuce (Lactuca sativa var. Great Lakes 366) grown on Tottori sand dune soil.

The of the soil solution was influenced by that of the nutrient solution. Calcium nutrition of lettuce was not influenced by the in the soil solution. However, the magnesium nutrition was improved at a low activity ratio, which resulted in the alleviation of the physiological injury.     

Behavior of nitrogen in the media supplied with the aqueous phase produced by methane fermentation as liquid fertilizer

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Behavior of nitrogen in the media was investigated when the aqueous phase produced by methane fermentation was supplied as liquid fertilizer.

When the aqueous phase was supplied to masa-soil,  included in masa-soil was nitrified to . Additionally, in masa-soil,  absorption was observed. On the other hand, in the case of coconut fiber and rockwool, has been hardly nitrified. From above results, it was determined that  toxic effect from the aqueous phase on tomato plants growth was inhibited by means of the progress of nitrification and  absorption by masa-soil.

However, nitrification was restrained so that  was fixed in masa-soil. On the other hand, in the sampled field soil,  was not fixed, and was nitrified immediately. In the field soil, there was a great deal of generated . In comparison with masa-soil.     

Characterization of zinc adsorption sites in two mineral soils

The adsorption of Zn, as compared with Mg, on two mineral soils, which differed in their major cation-exchange materials and with and without Ca-saturation, was measured in the presence of free CaCl₂.

The adsorption of Zn as well as Mg occurred on cation-exchange sites. The Zn adsorption data conformed to a two-term Langmuir equation. The presence of two kinds of adsorption sites and their numbers and bonding energies were deduced. However, the Langmuir approach was not adopted on the basis of comparison between the total number of the adsorption sites for Zn deduced and the CEC of the soils.

As an alternative approach, the selectivity coefficient as defined by the equation:

was calculated for each adsorption equilibrium and plotted against the amount of Zn adsorbed. This [Zn]_soil plot was used to estimate the capacities of the soil to adsorb Zn with specified affinities. The value varied between 1 and 1,000, whereas the corresponding value varied only between 0.5 and 1. The value was dependent upon the amount of Zn adsorbed, the status of exchangeable cations, and the major cation-exchange materials (montmorillonite VS. allophane-imogolite) in the soils. The importance of surface OH groups in allophane-imogolite as specific adsorption sites for Zn was suggested.     

Investigation and prediction spatial variability in chemical properties of agricultural soil using geostatistics

Determination of the chemical characteristics of soil for balanced fertilization on large scales is an important factor in achieving a precision agriculture. Laboratory analyses of soil properties are usually expensive and time consuming. Surmounting these problems is possible using geostatistics. Therefore, this research aims at selecting a proper interpolation method using 213 soil samples for alfalfa farmland in Hamadan Province, Iran. Various factors such as pH, EC, , , K, P, Fe, Zn, B and Co were measured. Ordinary kriging and co-kriging were assessed to derive maps of soil physico-chemical properties, using mean absolute error (MAE), mean bias error (MBE), root mean squared error (RMSE) and average kriging standard error (AKSE) as statistical criteria. Variography analysis indicated that the ranges of influence for pH, EC, , , K, P, Zn, Fe, B and Co were 65, 55, 78, 79, 75, 60, 50, 65, 70 and 30 km, respectively, and the measuring error varied between 0.366 and 0.843. The results revealed that, based on precision criteria, co-kriging was the best method for interpolating the chemical properties of soil. Finally, using to the co-kriging for each determined variable, a related zoning map for fertility management of the study area was prepared.