Liina Edesi

Soil compaction effects on soil bulk density and penetration resistance and growth of spring barley (Hordeum vulgare L.)

Abstract The weight of the tractor is not the only factor affecting soil compaction. Soil-management practices, such as the use of fertilizers and pesticides, also affect soil properties through an increased number of overriding. The aim of the current study was to investigate compaction effects on soil physical properties, such as dry bulk density and penetration resistance, and the growth of spring barley (Hordeum vulgare L.) as a monoculture. The five-year experiment was conducted on the Estonian University of Life Sciences’ research field at Eerika, near Tartu in 2001–2005. The soil of the experimental site is sandy loam Stagnic Luvisol. The treatments included were no compaction, one pass, three passes, and six passes. All passes were track-by-track. Measurements of soil and plant were made in the earing phase of barley and measurements of yield in the maturity phase of barley. The compaction treatment was conducted using an MTZ-82 tractor (total weight 4.84 Mg). Neither fertilizers nor herbicides were used. 5 years after compaction distinguishable subsoil and topsoil compaction was detected. Soil deformation increases with the number of passes; in the case of six passes soil bulk density increased by 0.15 Mg m−3 and penetration resistance by 3 MPa. However, there were no significant differences in the soil bulk density and penetration resistance between treatments compacted with one and three passes. The effect of compaction on soil bulk density was higher when the soil was compacted under wet conditions. Compaction decreased the quantity of barley shoots, their phytomass, and grain yield by more than 80%. In the second year of the experiment the dry weight of above ground biomass decreased by almost three times and shoots’ density by 1.5 times, compared with the first year results. In the third year of the experiment the biomass, plant density, and grain yield of barley were stabilized and no further decreases were detected in the following two experimental years. The results from the experiment revealed that even a low weight tractor can induce subsoil compaction and a high decrease of plant productivity by repeated passes over time.

The importance of solid cattle manure application on soil microorganisms in organic and conventional cultivation

Abstract Microbial communities are integral parts of the soil and their activity is very important to the functioning of the soil but the impact of different factors on soil microbial community composition is not well researched. Many studies have focused only on a few species. The aim of this study was to investigate the impact of treatment and sampling date on soil pH, abundance of total number of bacteria, molds, yeasts, mesophilic spore-forming bacteria, Fusarium spp., actinomycetes, azotobacteria, cellulose decomposers, denitrifying and nitrifying bacteria in organically (ORGGRM – green manure, and ORGFYM – green manure, solid cattle manure) and conventionally (CONFYM – solid cattle manure + mineral fertilizer and pesticides) cultivated soil. Fertilization with manure had positive direct- and after-effect (p<0.05) on the total number of bacteria, mesophilic spore-forming bacteria, nitrifying bacteria and cellulose decomposers, even in the CONFYM treatment. The abundance of yeasts was higher (p<0.05) in ORGFYM treatment (3.35×103) and 34–48% lower in CONFYM and ORGGRM treatments. The abundance of molds, Fusarium spp., and actinomycetes during the study in different treatments was similar but their abundance was significantly higher (p<0.05) when the weather in the sampling time was warm and humid. The negative impact of pesticides in CONFYM treatment occurred on the total number of bacteria, yeasts, molds, and denitrifying bacteria. The yeasts were most sensitive to pesticides; in study years, when the use of pesticides was very intensive, their abundance in CONFYM treatment decreased 72% compared with the ORGFYM treatment. The 4-year test results showed that although green manuring is considered an important management practice in organic cultivation, to maintain and increase the abundance of microbes in different microbial communities it is important to use other organic fertilizers such as animal manure in addition to green manure.

Effect of sulphur fertilization on grain yield and yield components of winter wheat

Abstract The effect of sulphur application on winter wheat yield and yield components on two different soils in northern Estonia and southern Estonia during 2004–2009 was investigated. Sulphur was applied with NS-fertilizer Axan or Axan Super at the rate of S 10 or 13.6 kg ha−1 accompanied with nitrogen background of N 100 kg ha−1, which effect was compared to effect of ammonium nitrate at the same rate of N. The rates of fertilizers were divided into two portions and applied at the growth stages 21–22 and 25–30. The effect of sulphur fertilization on the formation of wheat yield varied on a quite large scale depending on soil and weather conditions of trial locations. The yield components were closely related: when one component was changed, the other components sometimes compensated for grain yield. Sulphur deficiency symptoms appeared on the break-stony soil at Saku in a somewhat stronger form than on the pseudopodzolic soil at Auksi. The results of field trials conducted at Saku during the four years can be summarized as follows: the application of sulphur increased the number of ears per unit area by an average of 14.0% and the number of grains per ear by an average of 18.6%. At the same time, sulphur decreased the 1000-grain weight. As a final result, sulphur application on break-stony soil increased the wheat yield by 1.16 t ha−1 on average, i.e. by 23.0%. Sulphur application in trials conducted on pseudopodzolic soil at Auksi during years with different weather conditions in growing season proved highly effective in three of five trials. As an average of all trials in Auksi, the sulphur application increased the number of ears per unit area and the number of grains per ear by 23.9% and 7.7%, respectively. The grain yield increased under the influence of sulphur on the average of all trials conducted on pseudopodzolic soil by 1.25 t ha−1, i.e. by 22.4%.

The content and quality of protein in winter wheat grains depending on sulphur fertilization

Abstract On soils lacking in water-soluble sulphur, the sulphur fertilization of winter wheat, in general, increases the yields. There are not sufficient investigations about the influence of sulphur on the quality of yield. The objective of this work was to investigate the content and quality of protein in wheat grain depending on sulphur fertilization. The present study relies on field trials conducted on two different soils during 2004–2009. Sulphur was applied with NS-fertilizer Axan or Axan Super at the rate of S 10 or 13.6 kg ha−1 accompanied by a nitrogen background of N 100 kg ha−1. The rates of N- and NS-fertilizers were divided and applied at the beginning and at the end of tillering. At harvest, the grain samples from trial variants in four replications were taken, and the contents of crude protein, wet gluten, amino acids (lysine, threonine, cysteine, methionine) and gluten index in wheat grain were determined. Besides, the contents of amino acids were recalculated on their concentrations in protein. The protein and wet gluten contents in grain varied significantly depending on weather conditions of the trial years. On break-stony soil, sulphur increased the yield by 1.16 t ha−1 on average, i.e. by 21.7%. With increasing yields the protein and wet gluten concentrations in grain decreased. Under the influence of sulphur, the gluten index increased significantly – from 58 to 74, i.e. by 27.6%. In 2004 and 2005, sulphur increased the cysteine and methionine content in wheat grain. Although sulphur application in many cases decreased the protein and wet gluten contents in wheat grain, it improved the biological quality of protein because the concentrations of above-mentioned amino acids recalculated on their concentrations in protein increased significantly. The sulphur application in pseudopodzolic soil had a weaker effect on the grain quality than in break-stony soil.