EURASIAN JOURNAL OF SOIL SCIENCE

106-113

Authors: Dongdong Zhang, Yunli Wu, Xiaolin Zhang, Youfeng Zhu

Persistence of the fungicide myclobutanil in three tea orchard soils with different cultivating ages, neighboring wasteland and forest soils, and its influence on microbial activities in 2- and 50-year-oldtea orchard soils at three rates were studied in the laboratory. Dissipation data fitted well to first-order kinetic equation, except for sterilized treatments, in which neglected dissipation of myclobutanil was observed. At 25oC, the dissipation half-lives (DT50) at level of 1mg kg-1 were in the range of 15.07-69.32 days under non-flooded condition, significantly lower than flooded condition (p < 0.05), indicating that dissipation of myclobutanil was mainly driven by soil microorganisms under aerobic condition. Dissipation rate was significantly increased at 40oC compared to those at 4oC and 25oC for all five soils (p < 0.05). Under all incubation conditions, DT50 were lowest in 50-year-old tea orchard soil (p < 0.01). Correlation analysis between DT50 in tea orchard soils and soil properties showed that soil microbial biomass carbon was negatively correlated with DT50 under 25oC and 60% water holding capacity (p < 0.05). In general, soil microbial biomass carbon and dehydrogenase activity decreased as the concentration of myclobutanil and incubation time increased except 0.1 mg kg-1 spiked soils, in which soil dehydrogenase activity was stimulated after 10 days incubation.

121-133

Authors: Matthew Awopegba, Segun Oladele, Moses Awodun

Field investigations were carried out to evaluate the influence of shrub and herbaceous mulch types on soil properties and nutrient composition of maize (Zea mays L.) at the Teaching and Research Farm of the Federal University of Technology, Akure in the rainforest zone of southwestern Nigeria in 2013 and 2014 respectively. The shrub mulch; Gliricidia sepium and Tithonia diversifolia, herbaceous mulch; Calopogonium mucunoides and Moringa oleifera were applied at the rate of 5 t ha-1. Application of NPK (20:10:10) fertilizer at the rate of 200 kg ha-1 was included as the standard treatment for the experiments. The treatments were laid out in randomized complete block design (RCBD) with three replication. The growth, agronomic parameters and nutritional quality of maize (Zea mays L.) were monitored and determined in both experiments. Results indicated that herbaceous mulch types and NPK fertilizer significantly (P<0.05) increased the number of leaves, plant height and leaf area when compared with the control in both years. Significant increases in yield parameters over the control were obtained for the NPK fertilizer treatment. In 2013 and 2014 cropping season NPK 20-10-10 treatment significantly produced the highest cob yield but was not significantly higher than the yield from Gliricidia sepium treatment in 2014. Soil organic carbon, total nitrogen (N), potassium (K), and exchangeable cations were positively stimulated by herbaceous mulches while residual phosphorus (P) was increased by NPK fertilizer treatment. Mulched treatments significantly increased crude protein, carbohydrate, nitrogen, phosphorus and ash content of maize grain in both years of cropping season thereby improving nutritional content of maize grain. Therefore, shrub and herbaceous mulch treatments applied at 5t/ha-1 could be applied alternatively in lieu of scarce and expensive inorganic fertilizer for improved maize yield, soil properties and nutrient composition.

144-153

Authors: Mamdouh Sharafeldin Abdalkarim Shashoug , Mubarak Abdelrahman Abdalla , Elsadig Agabna Elhadi , Fatoma Ali Mohamed Rezig

A field experiment was conducted in the Experimental Research Farm of Omdurman Islamic University, Sudan to determine short-term effect of irrigation intervals (7 and 10 days) and sun-dried or composted sewage sludge, recommended mineral fertilizer on straw dry matter yield (SDMY) and N, P and K content of fodder sorghum and soil properties. In the 7 and 10 days irrigation intervals, composted, sun-dried sludge and mineral fertilizer have significantly increased SDMY over the control by 51, 98, 67 and 78, 19, 33%, respectively. Apparent N use efficiency (ANUE) in composted and sun dried plots irrigated at either 7 or 10 days was 9 - 36 and 16 - 74%, respectively. Reducing the irrigation interval has significantly increased salinity by 13%. Increasing irrigation interval has decreased bulk density by 5%. It could be concluded that, application of composted sludge is a useful practice for improvement of soil properties and consequent yield increase.

161-167

Authors: Chourouk Mathlouthi, Mariem Kacem, Zyed Mesticou, Philippe Dubujet

In this study, soil samples are extracted from a polluted site at different depths. Soils texture and pollutant presence are different with depth. Preliminary analyzes showed pollution by heavy metals. To simulate soil leaching operation in static condition, a series of leaching tests are conducted in laboratory column under conditions of upflow unsaturated soil. Electrical conductivity and pH measurements on the recovered leachate are performed. Different flow rates are tested. Comparison of different profiles shows that the dissolved pollutants are concentrated in the upper soil levels and disperse weakly in the lower parts which confirm the nature of anthropogenic pollution of heavy metals. Water mobilizes a high amount of dissolved ionic substances up to 80% of the initial concentration. The increase in flow rate requires more pore volume injected to achieve the maximum clearance rate. The down flow condition extracts a small amount of dissolved substances.

178-188

Authors: Maira Kussainova, Konstantin Pachikin, Olga Erokhina

Identification of land degradation is essential to check the problem and to implement the remedial measures needed. The study area falls under parts of foothill plains Zhetysu Ridge, Kazakhstan, that is an arid region in climate. Recent data on the status of study area refer to the 80s of the last century, and the intensive use of them led to a significant anthropogenic transformation. This study was carried out in 2015-2016 as part of a project aimed to study features and causes of land degradation in foothill plains Zhetysu Ridge, Kazakhstan. Under the conditions of rainfed soil degradation manifests itself in the development of erosion processes, agro depletion of soils, reducing the productivity of agriculture. The use of land for irrigation often accompanied by secondary salinization. In this regard, at present there is need to assess current state of the soil, with the identification of changes in their properties as a result of the impact of various anthropogenic factors and creation of new electronic soil maps and applied the powerful capabilities of advanced remote sensing (RS) and geographic information system (GIS) techniques to identify the geomorphological units and degradation risk assessment. Satellite imagery in addition to the field and laboratory studies to identify salinity-induced soil degradation was adopted in this study. Morphological, chemical and physical characteristics of soils in degraded sites in foothill plains Zhetysu Ridge, Kazakhstan, were depicted. The main results of a thorough evaluation of soil degradation in foothill plains Zhetysu Ridge, Kazakhstan, are presented. The data revealed that extent of salinity-induced degradation was generally related to some physical properties of soil, uncontrolled livestock grazing and previous soil management practices. These results are useful as the basis for designing soil conservation and restoration programs, as a base line for evaluating the performance of conservation programs and for assessing the impact of other soil-related activities (e.g. agriculture and livestock rising).