Methodical approaches for assessing the humidity of persistent plant wilting in pedosemes

Abstract

The research was conducted on the pilot field of land reclamation of the Dnipropetrovsk State Agrarian and Economic University. The field is located in the Nikopol district on the border of the northern and southern Steppe of Ukraine (Pokrov). For a more detailed study of the water-physical properties of pedosomes in the experimental field, a soil cut was made. Samples of soil were taken in layers of 0-10, 10-20 ... 90-100 cm from the inoculated section in pedosomes in a triple repetition.
On the basis of the maximum hygroscopic moisture content, the moisture content of the plants was weighed, taking the conversion factor of 1.34 - according to the instruction of the hydrometeorological service. In addition to calculating the humidity of plant weeping at maximum hygroscopic humidity, the method of direct determination of the indicator was used by growing seedlings in drying cups and bringing them to complete wilting.
  The indexes of humidity of steady wilting of plants in pedosomes by the calculated method and vegetation miniature method are determined. The results of the research for pedosomes indicate that the data obtained using the calculation method and vegetative thumbnail method differ significantly from each other. The reasons for the discrepancies of these approaches are established. The obtained results by the calculation-mathematical method indicate that the distribution of the values of BWR in layers is smooth, that is, there are no significant sharp changes in the values of the studied parameter in the layers. More variables are the values obtained when tested with vegetative miniatures. It was found out that for pedosens, the moisture content of persistent plant wilting is 7.87-11.93%. For the type of techno-type studied, the
uniform distribution of this indicator by the profile is characteristic. Only in the middle of the profile there is an increase in the humidity of plant wilting to 11,93%. For the type of techno-type studied, the uniform distribution of this indicator by the profile is characteristic. Only in the layer 40 - 50 cm there are higher rates. According to the results of regression analysis, it is proved that the salinity of the soil has the greatest influence on the assessment of the humidity of plant wilting. The constructed pedotransfer functions make it possible to reduce labor costs when determining the investigated hydrological constant and thus obtain an indicator that has obvious ecological significance.
The moisture content of the wilting is obtained by the method of miniatures, as it is environmentally sound, since it directly reflects the physiological state of plants, depending on the moisture content of the soil. But methodically, it is very labor intensive, and also that gives a lot of variable results. The latter circumstance also requires an increase in the number of experiments to achieve the required accuracy of estimates. The obtained pedotransfer function allows to obtain on the basis of less labor-consuming methods an indicator that has obvious ecological significance.
The results obtained indicate that both methods give similar estimates. But the differences between them are quite variable. Therefore, one can not restrict, using the calculation method, by changing the conversion factor. The most appropriate solution is to use a more complex regression model (note that the conversion factor is the simplest form of regression). The addition of a regression model to a predictor in the form of a degree of soil salinity (% dry residue) greatly improves the predictive properties of the model and justifies its application for practical purposes.
Such peculiarities of the accumulation of technosomes can be considered as negative for the growth of plants and the formation of the productivity of ecosystems. According to the results of regression analysis, it has been proved that the soil's salinity has the greatest influence on the moisture content of stable plant wilting. The constructed pedotransfer functions make it possible to reduce the loss of labor during the determination of this hydrological constant and obtain an indicator that has obvious ecological significance.