Geo-Engineering Study of Selected Soils for Cement Industry in Al-Kifil District, Babylon, Central Iraq

The research was conducted on nine pits for selected soils in Babylon, in the Al-Kifl region in particular. It aims to find the relationship between the physical and chemical properties of the studied soil and its suitability in the cement industry. Nine samples of different depths were taken with a simple description of the soil in the fieldwork stage. As for the stage of laboratory tests, it included testing the grain size distribution to find the percentage of sand, silt, and clay, and Atterberg limits to find plasticity. It was found through these tests that the soil is silty clay and has low plasticity except for samples no. 5, and 6, which were clayey soil with low plasticity. The relationship between physical properties depends on the property of the grain size distribution, as it is the function of the rest of the properties. Chemical tests of the samples and comparing the ratios of their oxides with the standard specifications of the Kufa plant laboratory turned out to be suitable for the manufacture of ordinary Portland cement, as the study area is considered a good quarry for the clays used in such industries.

Nutrient Use Efficiency Indices in Maize Hybrid as A Function of Various Rates of NPK in Mid Hills of Nepal

Field experiments were conducted to evaluate yield and nutrient use efficiency in maize in response to various rates of nitrogen (N), phosphorus (P) and potassium (K) in silty clay loam soil of Khumaltar, Nepal during 2019 and 2020. Three factorial randomized complete block designs with 27 treatment combinations were used in experiments, which were repeated three times. Three factors were N levels (150, 180, 210 N kg ha-1), P levels (40, 60, 80 P2O5 kg ha-1), and K levels (40, 60, 80 K2O kg ha-1). The results recommend to revise fertilizer dose since N210 kg ha-1 and K2O 80 kg/ha were optimum for increased maize production with grain yields of 10.95 t ha-1 and 10.54 t ha-1, respectively. Partial factor productivity, partial nutrient budget, internal efficiency, physiological efficiency, recovery efficiency, and agronomic efficiency of NPK for hybrid maize were mostly influenced by nutrient levels. Application of higher rate of P and K fertilizer improved maize N efficiencies, and case was valid for P and K efficiencies. Maize was more responsive to N and K fertilizer and lower rate of P application limited efficient use of applied N and K. To increase overall NUE, we recommend to revise dose of fertilizer for hybrid maize under mid hill condition of Nepal.

Effect of tillage and fertilizer doses on growth and growth indices of soybean (Glycine max L.) under conservation tillage systems

A field experiment was conducted during kharif season of 2019 at the Research Farm, Department of Agronomy, CSKHPKV, Palampur to study the effect of tillage and fertilizer doses on growth and growth indices of soybean under conservation tillage systems. The experiment consisted of twelve treatment combinations which included three tillage systems minimum tillage, minimum tillage with crop residue and conventional tillage and four fertility levels viz; 25 % recommended dose of fertilizer (RDF) , 50 %(RDF) , 75 % RDF and 100% RDF and which were tested in split plot design with tillage system in main plots and fertility levels in sub plots.The soil texture of experimental site was silty clay loam. Minimum tillage along with crop residues (T2)recorded significantly taller plants and higher dry matter accumulation followed by conventional tillage. Absolute growth rate, crop growth rate, dry matter efficiency, relative growth rate and unit area efficiency were significantly higher with minimum tillage + crop residue treatment. Application of 100 % followed by 75 % recommended dose of fertilizer resulted in significantly higher growth parameters and growth indices.

Study on Micro-Characteristics of Microbe-Induced Calcium Carbonate Solidified Loess

Microbial-induced carbonate precipitation (MICP) has outstanding characteristics in solidifying soil, such as good fluidity, ecological environmental protection, adjustable reaction, etc., making it have a good application prospect. As a typical silty clay, the composition of loess is fine, and the microstructure is quite different from that of sand. Previous research has found that the unconfined compressive strength of loess cured by MICP can be increased by nearly four times. In this paper, by comparing the changes of structural characteristics of undisturbed loess before and after MICP solidification, the mechanism of strength improvement of loess after MICP solidification is revealed from the microscopic level. Firstly, the microstructure of loess before and after solidification is tested by scanning electron microscope, and it is found that the skeleton particles of undisturbed loess are granular, and the soil particles coexist in direct contact and indirect contact, and the pores in soil are mainly overhead pores compared with the microstructure of solidified loess, it is found that the surface contact between aggregates increases obviously, and calcium carbonate generated by MICP is adsorbed around the point contact between aggregates, which makes the contact between soil particles change from point contact to surface contact. Then, Pores (Particles) and Cracks Analysis System (PCAS) is used to quantitatively analyze the pores of loess before and after solidification. The results show that the total pore area, the maximum total pore area and porosity of soil samples decrease, and the total number of pores decreases by 13.2% compared with that before MICP solidification, indicating that a part of calcium carbonate produced by MICP reaction accumulates in tiny pores, thus reducing the number of pores. One part is cemented between soil particles, which increases the contact area of particles. Therefore, some pores of loess solidified by MICP are filled and densified, the contact area between soil particles is increased, and the strength of loess under load is obviously improved.