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
A study of some Egyptian saline and alkali soils
For many centuries, soils of the Nile Valley and delta have been flooded annually
 by excellent water, and for the past 50 years, they have been irrigated perennially
 with stored water of somewhat lower quality.
 The present survey and field observations, while not permitting broad conclusions,
 do show some evidence that use of Nile water for perennial irrigation has had an alkalizing
 influence. The occurrence of high exchangeable sodium content as well as of high salinity
 was usually associated with high water tables or poor permeability.
 The extensive saline areas in the fringe of the delta at or below sea level are capable
 of reclamation, usually by effective drainage plus leaching. Some portions of these
 areas contain sufficient exchangeable sodium to make advisable the use of a soil amendment
 such as gypsum.
 Quick-method determinations of electrical conductivity of saturation extracts, soluble
 divalent cations, gypsum requirement, and cation exchange capacity served to classify
 the soils, explain observed differences in plant growth and in permeability, and to
 outline reclamation procedures.
 Pot-culture studies indicated that large-sized containers can be used efficiently
 for studying fine-textured, alkali soils, and that such studies are a useful preliminary
 to field tests of reclamation procedures.
Kinemamtic analysis of flying-saw vehicle
The paper analyzes the kinematic motion of the flying-saw vehicle.After the analysis,it is concluded that the ac- celerating periods and decelerating periods in both forward and backward directions will follow sin~2αcurve and,in order to increase the sawing dimensional accuracy,flying-saw vehicle must come back as soon as possible while acceleration remains constant.Based on this premise,the paper gives out the equations of kinematic motion of the flying-saw vehicle in every sta- ges and one example result in a common situation.By now this method has been used in the real situation.