Thoroughly updated and revised, this second edition of the bestselling Soil Sampling and Methods of Analysis presents several new chapters in the areas of biological and physical analysis and soil sampling. Reflecting the burgeoning interest in soil ecology, new contributions describe the growing number and assortment of new microbiological

Symposiumverslagen over: de omvang van ureum als meststof op de wereldmarkt; bodem-, milieu- en beheersfactoren die de ammoniakvervluchtiging beinvloeden; factoren die de ureumhydrolyse beinvloeden; de chemische balans m.b.t. de ammoniakvervluchtiging; modelmatige weergave voor het voorspellen van de vervluchtiging; vergelijking van methoden voor ammoniakmetingen; ontwikkelingen omtrent de toepassing van remstoffen bij de urease-vorming; mechanismen bij de urease-vorming; ammoniakvervluchtiging van ureumfosfaatmeststoffen

The purpose of our present work is to review the fundamental studies on inhibition of soil urease activity and the applied studies on improving efficiency of urea fertilizers by inhibition of soil urease activity. The general literature on these topics covers 65 years, and the patent literature comprises a period of nearly 40 years. Studies related to inhibition of soil urease activity were performed in a great number of countries' well representing all the continents. Full texts of the papers describing these studies were published in one of 18 languages·'. The literature data reviewed are structured into 10 chapters, 81 subchapters, and 224 sections. The bibliographical list consists of 830 papers cited. ·In alphabetical order: Argentina, Armenia, Australia, Austria, Belgium, Belorussia, Brazil. Bulgaria, Canada, China, Costa Rica, Cuba. Czech RepUblic, Egypt, Estonia, France, Georgia (Gruzia), Germany, Hungary, India, Iraq, Ireland, Israel, Italy. Japan, Kazakhstan, Lithuania, Malaysia, Moldova, Netherlands, New Zealand, Pakistan, Philippines, Poland, Romania, Russia, Saudi Arabia, Slovakia, South Africa, South Korea, Spain, Sri Lanka. Sudan, Sweden, Thailand, Turkey, Ukraine, United Kingdom, United States of America. Uzbekistan .

Fertilizer consumption has increased three fold during the past 30 years. It reached one million nutrient tones in 1980/81, two million tons in 1992/93 and three million tons in 2002/03. Urea, today, is made in approximately 75 factories worldwide with a total capacity approaching 100,000,000 tons annually. Urea hydrolyzed by urease. Sodium Thiosulfate (ST) has been reported to inhibit nitrification and urea hydrolysis and thereby reduces volatilization of urea nitrogen as ammonia from soils fertilized with urea. A laboratory experiment was carried out by adding ST to urea (10 % by volume). We evaluated ST as a soil urease inhibitor by studying its effects on urea hydrolysis. Encouraging results were found in reducing NH3 losses when ST was applied it reduced NH3 losses in cotton 35.13%, 31.65% and 35.35%, 32.77% in Rice soils in first and second experiment respectively. It functions as urease and nitrification inhibitor.

"Ammonia (NH3) volatilization from agriculture has negative impacts on human and ecosystem health (Galloway et al., 2003), and represents an extra expense for producers, who often over apply fertilizer to compensate for losses of nitrogen (N) (Good et al., 2011). Further research into the impact of different drivers on NH3 volatilization is required to recommend techniques to mitigate losses to producers; specifically, more research is needed on the impacts of soil water content (SWC), soil aggregate size and soil type on NH3 volatilization from subsurface-banded urea. Flux increased with greater initial SWC (P ≤ 0.05). This was likely caused by a more rapid and complete hydrolysis of urea in the wetter treatments at the beginning of the experiment. The largest aggregate size soil emitted more NH3 than the smaller size treatments (P ≤ 0.05). The presence of large macropores in the larger size treatments likely caused enhanced NH3 diffusion as the total ammoniacal nitrogen (TAN, the N present in solution in the form of NH3 and NH4+) solution in the soil had more exposure to the air. A stepwise analysis of the results from the soil type experiment showed that cation exchange capacity (CEC) was the only significant factor affecting cumulative NH3 emissions amidst the group of measured soil characteristics. CEC of soil is also highly correlated with several of the other factors tested, such as clay content and titratable acidity. The validity of small-scale measurements of NH3 volatilization from urea-fertilized fields has been questioned in the literature because vertical NH3 concentration gradients may change at the edge of the measurement plot and result in erroneously high emissions calculated from wind-tunnel NH3-flux measurements. This 'oasis effect' was studied using two, 22-m long wind tunnels constructed indoors over soil plots fertilized with surface-applied urea (20 g N m-2). Measurements of NH3 concentration in the air taken every 2 m along the tunnel were used to test for the oasis effect during two weeks following urea application. The NH3 flux calculated for each section of the tunnels did not indicate a reduction in the flux along the tunnels as predicted in the literature. The oasis effect was also tested for by analysing the shape of the air NH3 concentration vs. fetch profiles. Only 6% of the 62 measurement periods between the two tunnels when there was significant NH3 volatilization indicated the possibility of an oasis effect with a significant negative quadratic effect of fetch on NH3 concentration (P ≤ 0.05). For the other 94% of the NH3 volatilization periods, the NH3 concentration above the plot increased linearly with fetch (P ≤ 0.05), indicating the absence of the oasis effect for those periods. We also tested possible oasis effects by checking whether the NH3 flux was impacted by background air NH3 concentration inside the tunnel. The data from both tunnels was combined and analysed in four groups based on the background concentration difference, and none of the four groups indicated that the concentration difference was a significant regression parameter for flux difference in the tunnels (P ≤ 0.1). We propose that the absence of an oasis effect in the present study was the result of the dominant role of the NH3 source intensity over the air NH3 concentration as drivers of the volatilization rate. Our results indicate that wind tunnels measurements of NH3 volatilization over small surfaces fertilized using urea are not impacted by an oasis effect." --