EURASIAN JOURNAL OF SOIL SCIENCE

85-91

Authors: Hina Javed , Aneela Riaz , Amjad Qureshi , Komal Javed , Fakhir Mujeeb , Fraza Ijaz , Muhammad Saleem Akhtar , M. Asif Ali , Rehman Gul , Muhammad Aftab

Environmental stresses such as drought, temperature, salinity, air pollution, heavy metals, pesticides, and soil pH are major limiting factors in crop production because they affect almost all plant functions. Soil salinization is a serious stress condition causing major problem for crop productivity. To combat this salinity stress, Plant growth promoting rhizobacteria (PGPR) is considered as innovative, effective and ecofriendly approach. Plant growth promoting rhizobacteria (PGPR) have various direct and indirect mechanisms which can be correlated with their ability to form biofilms, chemotaxis, and the production of exopolysaccharide, indole-3-acetic acids (IAA) and aminocyclopropane-1- carboxylate (ACC) deaminase Investigations on the interaction of PGPR with other microbes and their effect on the physiological response of crop plants under different soil salinity regimes are still at an incipient stage. An experiment was conducted to investigate the effect of PGPR on lowering down the salt stress. Treatments were control (T1), Salt tolerant isolate KH-1 (T2), Salt tolerant isolate KH-2 (T3), Salt tolerant isolate KH-3 (T4), PGPR-I (Pseudimonas) (T5), PGPR-II (Azotobacter) (T6). Rice was sown under saline conditions at Soil Salinity Research Institute, Pindi Bhattian. With the inoculation of salt tolerant PGPR, plant growth and yield was improved. Result showed significant increase in plant height, biomass and yield over control. Inoculation of salt tolerant isolate KH-2 produced maximum grain yield in rice (4267 kg/ha) followed by PGPR-II and it was statistically significant from all other treatments along with control. It is concluded that with the application of salt tolerant isolate (KH-2), there is significant increase in rice production.

105-118

Authors: Mulugeta Demiss , Tekalign Mamo , Sheleme Beyene , Selamyihun Kidanu

Nutrient depletion and imbalance are among the major attributes that contribute to declining soil productivity in the highlands of Ethiopia. The blanket fertilizer recommendation, which considered only urea and Di-ammonium phosphate (DAP), was used over the past four decades to improve soil fertility for enhancing crop production. Nevertheless, the average national yields of small cereal including teff were low, despite application of nitrogen and phosphorus (NP) fertilizers. On-farm trials were conducted in the 2015/16 and 2016/17 cropping seasons at 18 locations on Ethiopian highland Vertisols to determine the response of teff to potassium (K) fertilization along with other limiting nutrients. Five K levels (0, 30, 60, 90 and 120 kg ha-1) in the form of murate of potash (KCl) were used in randomized complete block design with three replications. Separate analysis of variance was conducted for each sites and year. Least Significant Difference (LSD) test at P ≤ 0.05 was used to separate means whenever there were significant differences. Analysis of variance revealed a highly significant difference (P < 0.01) between treatments in both straw and grain yields and tissue nitrogen (N) and K concentrations of teff over the two-cropping seasons in 67% of the test locations. Additionally, responses to K were obtained on soils with available K test ranging between 166 and 282 mg kg-1. The Ca: K and Mg: K ratios were strongly and negatively correlated with relative yield and the correlations suggest that soil with Ca: K > 50:1 and Mg: K >15:1 are likely to respond to potassium fertilization. The yield advantage accrued due to K application ranged from 30 to 77% in 2015/16 and 8 to 51% in 2016/17 seasons. The economic optimum K fertilizer application rates varied between 60 kg K ha-1 in 44% of the sites to 90 kg K ha-1 in 23% of the sites. The findings highlighted the need for revisiting fertilizer program to enhance the yield and nutrient uptake of teff in K responsive soils and developing critical levels for K in the study sites.

126-139

Authors: Sezai Delibacak , Lyudmila Voronina , Ekaterina Morachevskaya , Ali Rıza Ongun

Sewage sludge is an important type of organic wastes among the various categories of solid waste. Organic matter resources in soils are relatively low and frequently require replenishment. Therefore, the use of sewage sludge in agricultural soils is a desirable method of their utilisation. The addition of sewage sludge to soils may be an inexpensive and effective alternative to the methods applied currently (mineral fertilisation, manure etc.). In spite of the undisputable advantages resulting from the application of sewage sludge in agriculture, it also involves some serious threats. Among those we should mention the presence of pathogens, heavy metals, and organic pollutants. In the current scenario of increasing global population, the generation of solid wastes like biosolids is bound to increase remarkably. Improper and unscientific disposal of biosolids results in several environmental issues such as surface and groundwater contamination, degradation of land, and food chain contamination. According to the principles of waste management hierarchy, agricultural recycling of biosolids will be a more environmentally preferred option over the traditional disposal methods. Utilizing the potential of biosolids to recycle valuable plant nutrients and as an effective soil amendment will not only help in sustainable management of this waste but also in minimizing the negatives associated with its traditional disposal. Every country must obey their regulations and legislations for managing their sewage sludge as a basic solution for use of sewage sludge in agricultural soil.

151-164

Authors: Zeynep Demir

Effects of different cover crops (CCs), mechanical cultivation and herbicide treatments on some soil chemical properties [pH, EC, total N, available P, exchangeable cations (Ca, Mg, K, Na) and the DTPA-extractable micronutrients (Fe, Mn, Zn, Cu)] and basal soil respiration (BSR) were investigated in a cherry orchard from 2013 to 2014. The present study was conducted in a cherry orchard located at the Experiment Station of Black Sea Agricultural Research Institute in Samsun province on the Northern side of Turkey. CC treatments, included Trifolium repens L. (TR), Festuca rubra subsp. Rubra (FRR), Festuca arundinacea (FA), T. repens (40%)+F. rubra rubra (30%)+F. arundinacea (30%) mixture (TFF), Vicia villosa (VV) and Trifolium meneghinianum (TM). Control treatments included mechanical cultivated (weed-free), herbicide treated (weed-free) and control plots, i.e., bare ground plots (with no cover crop) were allowed to become weedy. The experiment was conducted in a randomized complete block design with four replicates. The CCs were mowed in the flowering stages of the plants. After 90 days following seed harvest, soil samples were collected from two depths (0-20 and 20-40 cm) in each plot. All cropping species showed positive effects on soil chemical properties and BSR. The CC treatments decreased soil pH and exchangeable Na and increased EC, total N, available P, exchangeable cations (Ca, Mg, K) and the DTPA-extractable micronutrients (Fe, Mn, Zn). Effects of mechanical cultivation and herbicide treatments on soil chemical properties and BSR values were not found significant for both soil depths as compared to control (p<0.01). Results of the study showed that CCs, especially TR and VV treatments as legume plants improved soil chemical properties and BSR values in short term period. However, longer term studies are needed to evaluate the long-term effects of these sustainable management practices which have the potential to improve soil quality variables are encouraged.

173-185

Authors: Fikrey Tesfay , Kibebew Kibret , Aster Gebrekirstos , Kiros Meles Hadigu

In Ethiopia, rehabilitation of the natural resource-base in degraded lands through area exclosures has become a necessary intervention, albeit empirical studies on the impact of these exclosures are limited. This study was conducted to investigate changes in selected soil properties along exclosures’ age and slope positions in Kewet district, central dry lowlands of Ethiopia. Soil samples were collected from three slope positions of three purposively selected exclosures of 5, 15 and 20 years old and one adjacent open grazing land from 0-10 cm soil depth for analysis of pertinent soil properties. The effect of exclosure age on bulk density, contents of sand, clay, organic carbon, total nitrogen, available phosphorus, CEC, and exchangeable Mg+ and K+ was significant (P<0.05). All exclosures had low bulk density (1.14-1.16 g cm-3) as compared to the grazing land. Higher available water content (173 mm m-1) was recorded in the old exclosure. Soil organic carbon ranged from 2.58% (young exclosure) to 3.37% (middle age exclosure). Soil total nitrogen increased from 0.24-0.34%, while available phosphorus increased from 27-34%, from young to the old exclosure respectively. However, the influence of exclosures’ age on other soil properties was not significant. The young exclosure had the highest CEC (57 cmolc kg-1), whereas the grazing land had the highest total nitrogen and exchangeable Ca2+. From this result, it can be concluded that area exclosures, if managed properly, can improve some of the dynamic soil properties of open degraded grazing lands in the dry lowlands of Ethiopia.