EURASIAN JOURNAL OF SOIL SCIENCE

292-297

Authors: Ayten Namlı , Hanife Akça , Muhittin Onur Akça

The objective of the study was to investigate the survival of earthworm Eisenia fetida during vermicomposting of Sugar Industry wastes. These wastes are called Decanter sludge (DS) and Press filter waste soil (PKF). To achieve the objective a laboratory-based experiment was performed 12 weeks under controlled conditions. Eleven different mixtures were prepared by mixing DS, PKF and farmyard manure (FYM) in different ratios. During the incubation time, earthworms survived in treatments which included less than 50% DS or 50% PKF. The number of earthworms increased significantly in all treatments from 6 to 90 (P<0.05) during the experiment period. Chemical properties (pH, EC, OM, Total Nitrogen, Lime) and heavy metal contents of sugar industry vermicomposts were in accordance with the standard compost limits. Results of the present study indicated that the worms did not live in the medium containing more than 50% of the PKF and 50% of the DS. Vermicompost can be obtained from production wastes of sugar factory by applying vermicompost process on Decanter Sludge at the maximum ratio of 50% or its mix with PKF along with FYM. Use of DS and PKF as feed materials for vermicomposting can assist to turn the wastes into precious materials.

306-313

Authors: Alexander Sadovski , Mariya Ivanova

Measuring soil water-physical properties is laborious, time-consuming, and expensive. That provokes a lot of scientists to estimate them which action is troubled by the usage of different soil texture classification systems. The study proposes a rapid, reliable, and universally applicable methodology for soil textural transformations between different classification systems. The method of discrete mathematics is applied to make the conversion of particle-size classes from the Kachinsky system, which is used in Bulgaria to the International systems. Three different data sources were used to determine the water-physical properties of soils from textural data - 376 soil profiles from Bulgaria, extraction from the SoilGrids system for the Plovdiv district in Bulgaria and data from CanSIS/NSDB database. The relationship between the dependent variables field capacity (FC), wilting point (WP) and bulk density (BD), and independent variables sand, silt, and clay soil content was sought in the form of a regression equation. The applied stepwise regression procedure produces a close dependence between the soil texture and its water-physical properties.

321-328

Authors: Sabina Devkota Regmi

Climatic variability is one of the most significant factors influencing year-to-year crop production, even in high yielding and high-technology agricultural areas. Many studies have attributed variation in yield and crop response to N fertilizer in general terms to differences in varietal characteristics, but few attempts have been made to systematically disentangle the contributions of the genotype from other factors as climatic conditions. In this study, we used ORYZA V3 rice crop model to evaluate impact of climatic variability on optimum nitrogen application rate in rice cropping system. The results show that, solar radiation and N management practices play important roles in the response of N in grain yield. Maximum and minimum temperature has less effect on the grain yield compared to the solar radiation. Optimum N was higher in the dry season compared with the early wet season. Optimum N rate for the grain yield was around 200, 150 and 100. Nutrient use efficiency (NUE) was higher in early wet season (EWS) and late set season (LWS) in higher rate of nitrogen compared to the dry season (DS). Observed grain yield and simulated grain yield was almost similar in both seasons. The ORYZA simulation model performs well for estimating optimum N application.

339-348

Authors: Bilal Cemek , Recai Oktaş

The quality of groundwater plays an important role in irrigation management and planning. The most commonly used method when classifying the irrigation water quality is the United States Soil Laboratory (USSL) diagram. Fuzzy logic approach is one of the widely used methods produced more precise and accurate results according to the USSL diagram. A rule-based, fuzzy logic irrigation water quality (FL-IWQ) were evaluated by using electrical conductivity (EC), sodium adsorption ratio (SAR), and residual sodium carbonate (RSC) values of groundwater in irrigation, in Bafra plain. The FL-IWQ defuzzification methods-center of area (COA), mean of maxima (MOM), least of maxima (LOM), and (SOM) were selected and compared with quality values of groundwater in irrigation. Based on the results of the FL-IWQ defuzzification methods with quality values of groundwater in irrigation, the determination of coefficients for COA, MOM, SOM and LOM were 0.9874, 0.9755, 0,9574 and 0.9453, respectively. Results obtained from FL-IWQ revealed that there has been 93% general agreement with the results obtained from the USSL diagram and RSC classification. The developed fuzzy model produced more reliable results for groundwater in irrigation than that of the USSL-diagram and RSC classification. The study suggests using proposed fuzzy model as a promising alternative to the traditional ones for classifying the quality of groundwater in irrigation under uncertain conditions.

356-361

Authors: Tatiana Bauer , Tatiana Minkina , Svetlana Sushkova , Vishnu Rajput , Andrei Tereshenko , Aleksandr Nazarenko , Saglara Mandzhieva , Andrey Sushkov

Biochar is widely used sorbent for soil remediation but the mechanism of its effect on immobilization of metals and particular processes of metal transformation are still unclear. We designed an incubation experiment to investigate the impact of wood biochar to copper (Cu) contamination in Calcaric Fluvisols Loamic. The efficiency of biochar implementation for reduction of Cu mobility in soil has been studied using combined method of heavy metal fractioning (Minkina et al., 2013). It was shown that the use of sorbent into polluted soil results in the change of fraction-group composition of metal compounds, fixation of Cu due to reduction of weakly bound forms and increase of the part of residual and metal fractions strongly bound with organic matter. Decrease of pollutant mobility occurs along an increase of the dose of a sorbent. The greater effect was observed after use of biochar in the concentration 2.5 %. Thus, the present study demonstrates the possible remediation of soil contaminated by heavy metals using biochar and provides a particular strategy for remediation of soils contaminated with Cu.

194-201

Authors: Nalan Kars , Orhan Dengiz

Soil pollution, influenced by both the natural and anthropogenic factors, significantly reduces environmental quality. This research was carried out in some micro catchments located on Ordu province of Black Sea Region-Turkey in order to determine potential ecological risk index based on heavy metal elements (HMs) for organic farming. For this purpose, 166 soil samples (0-20 cm) were taken from the study area and some physical and chemical and HM concentrations (Cd, Cu, Cr, Ni, Pb and Zn) analysis were done. In this study, it was determined; i-) some physical and chemical properties of catchments’ soils, ii-) HM contents and the correlation relation between physico-chemical properties of soil and HM concentrations and iii-) potential ecological risk index (PERI). PERI was calculated using the data obtained to evaluate the environmental risks of HMs in the region. The results showed that Cu concentration in 3%, Cr in 0.6% and Ni in 4.8% of the soil samples exceeded the threshold levels whereas, the concentrations of other HMs were lower than the critical values. Statistically, it was also found significantly positive relationships between sand content and Cu of soils whereas, it was determined significantly negative relationships between EC and Cu. In addition, according to the obtained PERI results, while 54% of total soil samples were low while, 42% of them were moderate class. Only 4% of them were classified as significant ecological risk level. Moreover, according to mean potential ecological risk index of these HMs, it can be ordered as Cd>Pb>Cu>Ni> Zn>Cr.

208-221

Authors: Zeynep Demir

Effects of different cover crops (CCs), mechanically cultivation and herbicide treatments on soil organic matter (SOM) content and some physical properties of soils were investigated in a cherry orchard with clay soil in 2013 and 2014. The present study was conducted in a cherry orchard located at the Experiment Station of Black Sea Agricultural Research Institute in Samsun province in the Northern region of Turkey. As the CCs, 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) were utilized. Experiment also included plots mechanically cultivation (MC), herbicide treatment (HC) and control (C) plot without CCs. Experiment was conducted in randomized complete blocks design with four replications. The CCs were mowed in the flowering period of the plants. After 90 d following seed harvest, soil samples were collected from two depths (0-20 and 20-40 cm) in each plot. The CCs treatments decreased bulk density, volumetric water content, relative saturation, penetration resistance and increased SOM, field capacity, permanent wilting point, available water capacity, total porosity, gravimetric water content, mean weight diameter, structural stability index. The differences in the SOM contents and physical soil properties of all treatments as compared to the control were not found to be significant for the 20-40 cm soil depth in both years of experiments. The CCs, especially TR and VV treatments as legume plants improved SOM and physical soil properties, but longer term studies are needed to evaluate the long-term effects.

231-241

Authors: Marina Burachevskaya , Tatiana Minkina , Tatiana Bauer , Saglara Mandzhieva , Coşkun Gülser , Rıdvan Kızılkaya , Svetlana Sushkova , Vishnu Rajput

This study is aimed at elucidating the fractionation of Cu and Zn in Haplic Chernozem and its alteration under the contamination to evaluate the extraction selectivity of different extractants and thus the efficiency of three sequential extraction schemes (Tessier and McLaren five-step and modified BCR three-step methods). General trends in the distribution of Cu and Zn speciations revealed with these three fractionation schemes suggest that they can be applied for the soils and the obtained results can be compared. Low mobility of potentially toxic metals (PTM) in the studied soil is suggested not only by their high content in residual fraction, but also by low contents of exchangeable and carbonate bound fractions (not more than 4-5 % Cu and 5-7 % Zn in the first two fractions). The highest contribution to the absorption and retention of Cu delivered from anthropogenic sources is made by organic matter and sesquioxides (up to 29 %); for Zn, by the nonsilicate Fe and Mn compounds (up to 25 %). However, the pattern of PTM extraction from soils varies during the application of different fractionation methods. The Tessier method is distinguished by a higher extractability relative to organic matter and sesquioxides. Therefore, this method is more informative for the contaminated soils. The McLaren method makes it possible to track the weakly bound species of compounds without the risk of involving other soil components. The BCR method is marked by simplicity of application and, therefore, recommended only for the noncalcic or low-calcic soils.

254-263

Authors: Nabil Charchar , Laid Bouchaala , Hani Bouyahmed , Abd El-Fatteh Gherib , Amel Lehout

The ecological importance of soil bacteria is not limited to their number or biomass, although these parameters contribute greatly. Indeed, their main asset lies in their great genetic and functional diversity.This study aims to determine heavy metal contamination levels of the soils of an abandoned mining area of Sidi Kamber (Skikda), impact of heavy metals on bacterial communities and the possible risks that can affect the ecological balance of this area. Soil samples from three zones (Zone A, B and C) were collected from the top layer (0–20 cm) of mining area. Chemical analysis (pH, organic matter, total organic C, total N, available P, and cation exchange capacity, metal content of (Pb, Cu, Cd, Zn and Ni) and bacterial analysis were carried in center for biotechnology research CRBt. Our results show that the mining area is characterized by an acid pH. Significant variations were observed for edaphic parameters (organic matter, total organic C, total N, available P and cation exchange capacity) between three sampling zones. The overall area was severely polluted with Cu, Cd, Pb, Ni and Zn with a total concentration far exceeding international standards. The bacterial load and diversity were relatively high with a significant variation between the three zones. The PCA analysis of the soil's characteristics indicates that the organic matter and the cation exchange capacity affect the distribution of the metallic trace elements in the soil and allowed us thus to a clear separation of the studied zones.

275-281

Authors: Reda Ragab Shahin , Hassan Ahmed Khater

Sekem commercial organic farm was chosen for the present work; it is located at Belbeis 20 Km northeast of Cairo city which represented sandy soils. Five plots in Sekem farm were chosen to represent different periods of organic farming application, i.e. 0, 12, 15, 18 and 23 yrs. Surface (0-20 cm) and subsurface (20-40 cm) soil samples were collected in both winter and summer season. The collected soil samples were subjected to the dry sieve analysis to determine and separate the dry aggregate size of ˂0.25, 0.25-0.50, 0.50-1.00 and 1.00-2.00 mm diameter. The distributions of total organic carbon were studied in the whole soil and its aggregate fractions. The data showed that total organic carbon significantly increased by increasing the period of organic farming in the surface samples especially in the longest period of organic farming. Total organic carbon was concentrated in the finest aggregate fraction (˂0.25 mm) for both summer and winter seasons and it was also increased by increasing the period of organic farming. The investigation of the humic and fulvic separates using infrared (IR) spectrophotometry, showed the dominance of carboxylic bands in fulvic especially in the subsurface soil samples which indicated its acidic function. Humic separates showed a relative increased in the intensity of aromatic bands as compared to fulvic separates with increasing the period of organic farming.

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.

1-9

Authors: Abdelmonem Mohamed Ahmed Amer

Sorptivity (S) has been defined in terms of the horizontal infiltration equation. At unsaturated conditions (at a very short time) S represents “maximum sorption capacity”, but in saturated conditions the sorption capacity decreases with the time. Over a long time of infiltration, sorptivity was not studied as a soil water parameter that could be determined. The purpose of this study is to apply derived equations depending on the infiltration functions to predict (1) soil water sorptivity (S) at infiltration capacity (unsaturated conditions) and at basic infiltration rate (Ib) (saturated conditions), (2) the hydraulic conductivity (Saturated Ks and unsaturated K(θ)) into capillary-matrix and non-capillary macro pores of soils. Five alluvial (saline and non-saline clay) and calcareous soil profiles located in the Nile Delta were investigated for applying the assumed equations. A decrease in S value was observed with an increase in soil water content. At steady infiltration rate (Ib), S decreased from 1.04 to 0.647cm.min-0.5 (i.e. S decreased by 37.79%) in average in calcareous soils and from 0.537 to 0.251cm.min-0.5 (53.25%) in alluvial clay soils. The steady Sw parameter was used in prediction of the hydraulic conductivities and the basic infiltration rate Ib , whereas, Sw is a suggested term at steady infiltration rate. The calculated values of Ib were corresponding to those obtained by infiltration experiment. This confirmed the significance of steady Sw as a new functional infiltration parameter. A matching factor u was calculated as a ratio between predicted Ib and the measured saturated hydraulic conductivity, Ks. The mean values of u were 0.895, 0.685 and 0.360 for calcareous, clay and saline clay soils respectively. Unsaturated K(θ) has been discriminated into saturated macro-pore K(θ)RDP and matrix unsaturated K(θ)h. The values of K(θ)RDP for macro pores remained higher than those for soil matrix pores (K(θ)h) in the studied soils. The highest value of K(θ) was obvious in calcareous soil profiles, while the lowest value was existed in saline clay soil. In conclusion, the predicted values of hydraulic conductivities of soil matrix (capillary) and macro (non-capillary) pores were reasonable and existed in the normal ranges of the investigated soils, indicating that the proposed equations are applicable and can be recommended to be used in coarse and fine textured soils with large scale of different properties.

18-23

Authors: Luiz Felippe Salemi, Rafael Pires Fernandes , Robson Willians da Costa Silva , Lara Gabrielle Garcia , Jorge Marcos de Moraes , Juliano Daniel Groppo , Luiz Antonio Martinelli

There have been a number of studies dealing with soil hydraulic properties. Yet, there is a poor discussion on the number of samples necessary to represent such variables that usually vary orders of magnitude in space. In the present paper, we examine the adequate number of samples for two soil saturated hydraulic conductivity (Ksat) data sets: (1) normal distribution (a 40 year-old pasture) and (2) non-normal distribution (primary forest). To assess the adequate number of samples in each case, we used for normal distribution, an statistical criterion of standard deviation lower than 5% compared to a high sampling effort (n = 25) as an indicative of a proper representation of Ksat variability. In the case of non-normal distribution, we used the same criterion but using median absolute deviation (a non-parametric statistics). Both data sets were available in Salemi et al. (2013) and were Ksat measured at 0.15 m soil depth for medium-textured inceptisols in São Paulo State, Brazil. For each data set, we simulated 10 ‘new’ samplings in which we calculated mean and standard deviation from sample 1 to 25 (for normal data) and median and median absolute deviation (for non-normal data). We found that, on average, at least 17 to 22 samples had to be collected to meet the adopted criterion for normal data whereas 20 to 25 had to be collected for non-normal data. Such numbers of samples exceed those used in a number of papers. Additional examples of this method with a light modification are given to establish number of samples in new study areas as well as to estimate number of samples when comparing two (or more) land-uses. Simple and practical procedures like those presented here could estimate the number of samples that adequately represents soil hydraulic properties variability.

34-42

Authors: Sani Issa Mahaman Sanoussi , Fatondji Dougbedji , Ezenwa Matthew , A.A. Okhimamhe , Ali Ibrahim , Isiah Sule

In the Sahel, mineral fertilizer micro-dosing technique is known for its benefits to provide higher nutrient uptake and higher crop yields. A study was set up at ICRISAT research station at Sadoré in Niger, which aims at evaluating the sustainability of the technology in the long-term with emphasis on soil nutrients dynamics. The study has started since 2008 and was laid-out in a randomized complete block design that involved two pearl millet varieties, three planting densities, and four nutrients management options. For this study, a sub-set of the treatments from this long-term experiment was used. The nutrient management factor, which includes 4 levels was considered. The most important findings obtained indicated that the change in soil nutrient was markedly different on the planting hills and that from between hill. The change in soil pH-H2O values on the planting was -7.06 % for the control plots and -9.57 % for the plots applied with NPK. The total nitrogen content has dropped in the two different plots. The amplitude of drop has lowered with the application of NPK micro-dosing on the planting hills with respectively -5.11 % and -12.45 % in the control plots and the micro-dose plots. Positive change in available P was significantly observed (P≤0.05) in soil between hill with 1.08% in the control plots and 15.97 % in the amended plots. Both grain yield and total dry matter showed similar trend in which decreased yield was obvious over the time. In 2008, an average grain yield of 732 kg. ha-1 and 989 kg. ha-1 was obtained respectively for the control plots and 6g per hill of NPK plots. Whereas in 2016, 146 kg. ha-1 and 218 kg. ha-1 were produced respectively for the control plots and the mineral fertilizer micro-dosing plots. These findings indicated that in the Sahel low-input based millet cropping systems, for the mineral fertilizer micro-dosing technology to be sustainable in the long term, the improvement and maintenance of soil fertility should be considered as the cornerstone.

52-59

Authors: Nalan Kars , Imanverdi Ekberli

The aim of this study was to set regression models based on correlation between yield parameters of maize plant (height, thousand seed weight and yield) and physical and chemical characteristics of soils and to determine applicability of obtained models in estimation of plant yield grown in soils of Çarşamba Plain. Regression coefficient (R), root mean square error (RMSE), index of agreement , model efficiency (ME) were evaluated to determine the validity of regression models between the yield components and physical and chemical characteristics of 40 soil samples taken from root zone of cultivated farms. Model associated with the relation between (i) plant height and bulk density (BD), field capacity (FC), clay and sand content wasn’t statistical significant (R= 0.53, p>0.05); (ii) thousand seed weight and soil electrical conductivity (EC), organic matter (OM), lime (CaCO3), nitrogen (N), phosphorus (P), potassium (K), Ca + Mg was characterized with a moderate R (R=0.79, p < 0.05), and (iii) seed yield and OM, N, P, K, copper (Cu), cation exchange capacity (CEC), CaCO3 indices has the highest R (R = 0.87; p <0.01). In general, statistical parameters were within the validity limits. The established regression models can be applied for the predicting of yield parameters of maize plant grown in the farmed areas of the region.

66-74

Authors: Mehmet Ali Demiral , Juan Carlos Melgar , Beatriz Contreras , Ayako Kusakabe , Murat Uygun , Seçil Küçük Kaya

In this study, one-year old grapefruit trees grafted onto sour Orange (SO) and C22 rootstocks were exposed to NaCl-induced salinity (approx. 6 dS m-1) in pot culture for two months under greenhouse conditions. The experiment was laid out in a randomized block design with eight replicates. The trees were irrigated with saline solution containing 0.1% liquid fertilizer “Miracle-Gro Liqua Feed 9-4-9” (N-P2O5-K2O) enriched with micronutrients. The experimental treatments consisted of three levels (4 mM, 8 mM, 12 mM) of foliar applied proline along with control application. Distilled water served as the control. During the experiment the seedlings were sprayed totally five times with ten days intervals. At the end of the treatment physiologically mature leaves, free of damage or defects, were sampled. Dried and ground leaf samples were used for chemical (Na and Cl) and biochemical (DPPH scavenging activity, reducing power, total phenolic content, proline) analysis. Spesific leaf area, leaf water relations and leaf gas exchange of the plants were also determined. Foliar PRO application decreased Na and Cl concentrations of the leaves, and improved spesific leaf area in the final dose. Water leaf relations, photosynthetic activity and biochemical parameters were affected positively even though some differences were determined between the cultivars.