Effect of gypsum and calcium carbonate on plant yield and chemical composition and calcium availability in a non-saline sodic soil
SummaryThe availability of Ca from different levels of gypsum and calcium carbonate in a non-saline sodic soil has been investigated. Different levels of tagged gypsum (Ca45SO4.2H2O) and calcium carbonate (Ca45CO3) (i.e. 0, 25, 50, 75, and 100 per cent of gypsum requirement) were mixed thoroughly in 3.5 Kg of a non-saline alkali soil (ESP, 48.4; ECe, 2.68 millimhos/cm). Dhaincha (Sesbania aculeata) — a legume and barley (Hordeum vulgare L.) — a cereal were taken as test crops. Increasing levels of gypsum caused a gradual increase in the yield of dry matter, content of Ca and K in the plant tops and Ca:Na and (Ca+Mg):(Na+K) ratios in both the crops. Application of calcium carbonate caused a slight increase in the dry matter yield, content of Ca and Mg and Ca:Na and (Ca+Mg):(Na+K) ratios in barley, however, in case of dhaincha there was no such effect. Gypsum application caused a gradual decrease in the content of Na and P in both the crops. Total uptake of Ca, Mg, K, N and P per pot increased in response to gypsum application. The effect of calcium carbonate application on the total uptake of these elements was much smaller on dhaincha, but in barley there was some increasing trend.Increasing application of tagged gypsum and calcium carbonate caused a gradual increase in the concentration and per cent contribution of source Ca in both the crops, although, the rate of increase was considerably more in dhaincha. The availability of Ca from applied gypsum was considerably more than that from applied calcium carbonate. Efficiency of dhaincha to utilize Ca from applied sources was considerably more (i.e. about five times) than that of barley
Reclamation of an alkali soil of the Hacienda series
A swamp culture regime in which water grass was grown for several months under very moist conditions has proved to be an important factor in the reclamation of an alkali soil of the Hacienda series. Gypsum applications of 4.22 and 12.47 tons per acre and sulfuric acid applications of 3.59 and 6.95 tons per acre, in conjunction with the swamp-culture pretreatment, showed marked beneficial effects on the subsequent growth of alfalfa. Statistically, the sulfuric acid applications were more effective than the gypsum applications, although there were no significant differences in yield between the high and low acid treatments nor between the high and low gypsum treatments. This suggests that lower applications than 3.59 tons of sulfuric acid and 4.22 tons of gypsum may be equally effective.
Synergistic Effect of High Temperature and High pH on the Destruction of Salmonella enteritidis and Escherichia co1i O157:H7.
This study was undertaken to determine if high temperature and high pH interact synergistically to enhance the rate of destruction of two important gram-negative foodborne pathogens, Escherichia coli O157:H7 and Salmonella enteritidis . The rates of destruction in NaHCO3-NaOH buffers at pH 7.0, 10.0, and 11.0 were determined at 35, 40, 45, 50, 55, 60, and 65°C. Use of an improved heating protocol eliminated a "tailing effect" at longer exposure times. The present study demonstrated that the combination of high pH and high temperature resulted in a highly significant synergistic interaction (P > F = 0.0001), which caused rapid death of both E. coli O157:H7 and S. enteritidis . This "alka-therm" technology might be used commercially to destroy gram-negative foodborne pathogens on various raw agricultural commodities.