Influence of Super Absorbent Polymer and Humic Acid on Maize Yield and Nutrient Uptake on Rainfed Alfisols

The advances and development in agriculture depend not only on mechanization and new hybrid seeds but also on the improvement of soil physical and chemical properties which in turn help to increase crop productivity in dry land soils. A field study was carried out to study the influence of superabsorbent polymer at 2.5 and 4.5 kg ha-1and humic acid at 15 and 30 kg ha-1 alone and their combinations with recommended 100% fertilizers on yield, uptake, and photosynthetic pigments of maize grown on rainfed alfisols at Regional Agricultural Research Station, Palem, Telangana. The experiment was laid out in randomized block design with three replications, consisting of nine treatments. Further, results showed that conjoint application of [email protected] kg ha-1 + humic acid@30 kg ha-1 along with 100% RDF package significantly increased the pooled grain and stover yield (7136 and 8457 kg ha-1) of maize. Irrespective level of hydrogel and humic acid combinations with 100% RDF increased the macronutrient uptake by grain and stover, which further build up the total uptake. A similar pattern was also observed in corresponding to grain and stover yield.The chlorophyll “a”, “b” and total chlorophyll content (1.81, 1.69 1.54; 0.69, 0.62, 0.55 and 2.65, 2.46 and 2.24 mg g-1 in fresh plant weight at 30, 60 and 90 DAS) significantly influenced by application of [email protected] kg ha-1+ humic acid@30 kg ha-1. In conclusion, the present investigation indicates the positive interaction between humic acid and super absorbent polymer which improved nutrient uptake and maize yield.

Mixture Compound Fertilizer and Super Absorbent Polymer Application Significantly Promoted Growth and Increased Nutrient Levels in Pinus massoniana Seedlings and Soil in Seriously Eroded Degradation Region of Southern China

Pinus massoniana is the pioneer tree species in the red soil regions of southern China, however, the serious understory soil erosion and nutrient deficiency in that region are the main factors restricting the growth of P. massoniana. This field study examined the effects of compound fertilizer and super absorbent polymer (SAP) on the physiology, growth characteristics, biomass, soil nutrient, plant nutrient content, and nutrient uptake efficiency of 1-year-old P. massoniana seedlings for 2 years at Changting, Fujian in South China. One control (no fertilizer, CK) and fertilization treatments were established, namely, single compound fertilizer application (0.94, 1.89, and 3.56 g⋅plant–1) and mixture compound fertilizer and SAP application (0.94 + 1.01, 1.89 + 1.01, and 3.56 + 1.01 g⋅plant–1). Fertilization significantly improved the physiological performance, root collar diameter growth, height growth, biomass, and nutrient uptake of the seedlings. Compared with other fertilization treatments, the mixture compound fertilizer and SAP application significantly improved the seedling photosynthesis, which meant that the SAP had a significant effect on promoting photosynthesis. Under the mixture compound fertilizer and SAP application, the whole biomass of the seedlings was higher than that of all other treatments. Fertilization significantly increased the nitrogen (N), phosphorus (P), and potassium (K) content in the soils, leaves, stems, and roots of the seedlings, respectively. The P content was the main factor affecting growth characteristics and contributed to 58.03% of the total variation in seedling growth characteristics (P < 0.01). The N:P ratio of CK in the soils, leaves, and stems were higher than that of all the fertilization treatments, indicating that the severely eroded and degraded region had little P and required much of P. The principal component analysis indicated that the F2S (1.89 + 1.01 g) was the optimum fertilization amount and method in this experiment. These results provide a theoretical basis for the fertilization management of P. massoniana forests with severely eroded and degraded red soil regions.

Effect of Curing Methods on Strength and Durability Properties of M30 Grade Concrete

This paper presents an experimental investigation on influence of different curing methods on the performance of M30 grade concrete. Different curing methods such as air curing, pond curing, intermittent curing, gunny bags curing, chemical curing and using Super Absorbent Polymer (SAP) by 0.3% of weight of cement are considered. Slump and compacting factor tests are performed to know the workability of fresh concrete. Compressive strength of hardened concrete is determined for concrete specimens cured by different curing methods. Durability in terms of carbonation resistance on hardened concrete is also performed as per IS 516 (Part 5/Sec 3, 2021) codal provisions. Depending upon the site conditions and availability of potable water, curing methods such as pond curing, intermittent curing, gunny bags curing, chemical curing and SAP curing can be adopted in site to achieve the expected strength and durability requirements. Keywords: Curing methods, Compressive strength and Carbonation resistance.

Influence of Super Absorbent Polymer on the Sulfate Resistance of Cement Mortar

Structures are easily corroded in the Salt Lake areas of China, especially in sulfate solution. This study was intended to settle the problem of sulfate corrosion failure of concrete structures, the influences of different contents of super absorbent polymer (abbreviated as SAP) on the working performance, mechanical properties, corrosion resistance and expansion performance of cement mortar were studied. The mechanism of SAP in mortar was analyzed and studied by SEM. The results showed that although SAP could slightly decrease the fluidity and strength of cement mortar, but it could remarkably improve the coefficient of resistance erosion of specimens and the inflation coefficient of cement paste. When the content of SAP was 0.3%, the sulfate corrosion resistance and expansion performance of specimens showed the best (the coefficient of resistance erosion and inflation coefficient of mortar specimens were 0.95 and 0.97, respectively). Besides, SAP could release much water in the hydration process, form irregular holes, and increase the porosity of mortar specimens. There would more hydration products generated and filled in the pores during the hydration process, thereby improving the sulfate resistance of mortar specimens. Therefore, this research provides theoretical guidance and basis for the study of sulfate corrosion damage of concrete structures in the future.

Development of Echo-LPT for the study of particle-wall interactions in dense suspensions

Examining the behaviour of dense suspensions has proven to be difficult, both experimentally and numerically. Using super water–absorbent polymer, PIV measurement was successfully conducted in a hydrogel suspension with a volume fraction (VF) of Φ =20% (see Zhang and Rival, 2018). However, due to the slightly refractive index mismatch, the image quality will degrade significantly as the particle loading of the hydrogel is increased. In order to achieve flow measurements in suspensions with high volume fractions, non-optical based techniques such as ultrasound imaging velocimetry (UIV) should be implemented. UIV has been developed for fluid dynamics applications and embraced by many researchers to study fluid flows (Gurung and Poelma, 2016; Jeronimo et al., 2019). Although, UIV provides useful information about the flow physics, it is unable to provide Lagrangian quantities such as particle trajectories, which is a key parameter to study entrainment and particle-wall interactions.