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Csorba S.,Szent Istvan University | Farkas C.,MTA Talajtani Es Agrokemiai Kutatointezet | Birkas M.,Szent Istvan University
Agrokemia es Talajtan | Year: 2011

The effect of different soil tillage systems on soil physical properties, especially the water retention functions (pF curves) decisive for the soil moisture regime, was studied in a split-plot field experiment set up on pseudomyceliar calcareous chernozem soil (Calcic Cernic Chernozem, WRB) formed on loess at the Józsefmajor Experimental Station of Szent István University. The experiment was carried out in a single-factor strip design on plots measuring 13 m × 150 m in three replications. The following soil tillage systems and tilling depths were applied: ploughing (SZ, 26-30 cm); disking (TÁ, 16-20 cm), disking combined with deep loosening (LT, L: 40-45 cm, T: 16-20 cm), shallow cultivation (SK, 12-16 cm); cultivation (K, 16-20 cm), and no tillage (DV). All the six treatments were investigated. The crop sequence was sunflower, winter wheat and maize between 2008 and 2010, with mustard as an intercrop in 2009. In the year analyzed, maize was sown on 4 May 2010. On all the plots basic tillage was carried out in autumn 2009. The soil structure in the various tillage treatments was characterized on the basis of pore size distribution. For this purpose single and dual porosity pF curves were fitted to the water retention values recorded for the soil layers in the individual tillage treatments. The dual porosity pF curve was found to give a better fit to the measured values than the single porosity curve for all the treatments. The soil macro- and micropore domains were used to evaluate the effect of different tillage systems on soil structure, as they strongly influence the soil moisture regime. These two domains could be clearly distinguished using the dual porosity pF curve. Studies were also made on the effect of direct drilling (without soil disturbance), ploughing, disking and the other agronomic measures on soil water retention characteristics. The no-tillage technology resulted in an almost constant macropore domain at various soil depths, while in the ploughed treatment the tillage depth could be clearly identified as changes in the pore domain. Differences could be observed between the tillage treatments both in pore size distribution and in the measured soil moisture content. In the complex function applied, the w value expressing the ratio of pore domains gave the best reflection of the individual effects of the tillage treatments on soil structure. It was found that under the given conditions, tillage using deep cultivation resulted in the most stable soil structure, most favourable for the water and air regimes.

The effect of microelement pollution at rates of 0, 30, 90 and 270 kg•ha-1 on winter barley was examined on calcareous sandy soil in the region between the rivers Danube and Tisza. The microelement salts were applied on a single occasion at the start of the experiment in spring 1995 in the form of Cr2(SO4)3, K 2Cr2O7, CuSO4, Pb(NO 3)2, Na2SeO3 and ZnSO4. The 24 treatments (6 elements×4 pollution rates) were each applied in three replications, giving a total of 72 plots, each measuring 7×5 = 35 m2. As generally observed on sandy soils, the growing site had a poor water regime, was prone to drought and was poorly supplied with macronutrients (NPK). The ploughed layer contained 0.7-1.0% humus and 2-3% CaCO3, and the groundwater was at a depth of 5-10 m. The whole experiment was treated each year with 100 kg•ha-1 each of N, P2O 5 and K2O active agents as basic fertilizer. The main results were as follows: - Due to the very dry weather in May and June the yields were very low. On uncontaminated soil the grain yield of winter barley was around 1.8 t•ha-1, while the total air-dry aboveground biomass only just exceeded 3 t•ha-1. In the 6th year of the experiment the carry-over effects of the 270 kg•ha-1 rates of Se and Zn proved to be toxic. This effect was felt mainly in the generative phase, with a 60-70% loss of grain yield. - In the Cr(III) treatment, the Cr content of the straw and grain did not rise significantly with the contamination rate, but in the Cr(VI) treatment the moderate accumulation was significant. Lead accumulation was only significant in the straw, remaining below the 0.1 mg•kg-1 detection limit in the grain even on contaminated soil. Compared with the control, there was a 2-2.5 times increase in Cu accumulation on average. The Zn content was 6-times higher in the straw and 3-times higher in the grain, while hyperaccumulation was recorded for Se in both plant organs (with a 470× increase in the concentration). The grain became unfit for human consumption in the Se treatment and at higher rates of Zn, and the straw for feeding purposes on soil treated with selenium. - On contaminated soil the maximum element uptake (g•ha-1) at harvest was as follows: Se 243, Zn 81, Cu 10, Cr and Pb 6. Assuming constant conditions, the phytoremediation of the soil would require 1111 years for Se, 3300 for Zn, 27,000 for Cu and 45,000 for Cr and Pb. - The specific element content of winter barley (1 t grain + the corresponding by-products) was found to be 28, 13, 28, 9 and 7 kg•t-1 for N, P2O5, K 2O, CaO and MgO, respectively. These data could be used as guidelines for the estimation of the nutrient requirements of winter barley by the extension service. - Soil analysis indicated that the NH4- acetate+EDTA-soluble Cr content increased in the 0-30 cm topsoil in the Cr(III) treatment, while in the Cr(VI) treatment the Cr maximum was detected below a depth of 260 cm and the whole soil profile was contaminated. Cu, Pb and Zn also accumulated in the topsoil, remaining at the application site even after the 6th year of the experiment. Like Cr(VI), the water-soluble Se could be detected throughout the 0-290 cm profile examined, so the total extent of the leaching zone could not be determined.

Interactions between potassium and boron were investigated in 1988 on a pseudomyceliar (calcareous) chernozem soil at the Experimental Station of RISSAC in Nagyhörcsök, using sunflower as indicator plant. Basic fertilization was applied at a rate of 100 kg each of N and P2O 5 per hectare. K2O rates of 0, 1000 and 2000 kg•ha-1 and B rates of 0, 20, 40 and 60 kg•ha-1 were applied in autumn 1987, after alfalfa as forecrop. The fertilizers were applied in the form of calcium ammonium nitrate, superphosphate, 60% KCl and 11% borax. The three K rates formed the main plots and the four B rates the subplots. Each of the 12 treatments was tested in three replications on a total of 36 plots arranged in a split-plot design. The ploughed layer contained around 5% CaCO3, 3% humus and 20-22% clay. The soil originally had good supplies of N, Ca, Mg and Mn, moderately good supplies of K and relatively poor supplies of P and Zn. The groundwater was located at a depth of 13-15 m and the area was prone to drought. During the growing period of sunflower there was 290 mm rainfall (close to the long-term mean), but May and July were extremely dry. The main conclusions were as follows: - The number of plants per hectare at harvest dropped significantly from 34,000 to 23,000 on the K control plots in response to B application. However, the lower plant density resulted in the production of larger flower heads, and greater thousand-seed mass and seed mass per flower head, thus preventing a loss of yield. On plots replenished with potassium, this negative effect of boron was not observed. The distribution of the total air-dry aboveground biomass (5.5 t•ha-1) was 2.1 for seeds, 2.1 for stems and 1.3 t•ha-1 for the flower heads. - The B content of sunflower organs was significantly increased by B fertilization, while K fertilization led to a significant or insignificant decrease. The largest quantity of boron (averaging 69 mg•kg- 1) was accumulated in the flower heads at harvest. This was around three times the mean B content of the stem and seeds. The K content of the plants was not modified significantly by K fertilization. - Na and Fe were mainly accumulated in the roots of 4-6-leaf plants, N, K, Ca and Mg in the shoots, Ca and Cu, as well as B, in the flower heads at harvest, and N, P, Zn and Cu in the seeds. There was a reduction in the N, P, Zn and Cu contents of the stem, while these elements accumulated in the seeds. - The element content of 1 t seed yield + the corresponding stem and flower head by-products amounted to approximately 46 kg N, 40 kg K (47 kg K2O), 27 kg Ca (38 kg CaO), 7 kg P (16 kg P2O5) and 7 kg Mg (11 kg MgO). These data could be used as guidelines for the estimation of the nutrient requirements of sunflower by the extension service. - The fertilizer requirements of sunflower, generally considered to exhaust the soil and have a high demand for nutrients, declined drastically in the case of combine harvesting, since most of the K, Ca and Mg was found in the by-products, which were not removed from the field.

Kodobocz L.,MTA Talajtani Es Agrokemiai Kutatointezet | Zsiros L.R.,MTA Novenyvedelmi Kutatointezet | Muranyi A.,MTA Talajtani Es Agrokemiai Kutatointezet
Agrokemia es Talajtan | Year: 2011

The efficiency of inoculating soybean and the host plant specificity of the inoculant strains was examined on chernozem soil under field conditions. The soybean (Glycine max L., Kurca) was inoculated at a rate of 80 kg seed/5×1011 CFU. In the course of the vegetation period, inoculation was supplemented by the application of a trace element solution. The results were evaluated by analysing plant and soil samples taken from 5×1 m for each treatment (uninoculated control; inoculated; inoculated + microelements). The comparative analysis of the microsymbiotic bacterium strains was carried out using the BOX-PCR method. No nodule formation was observed on the control plants. The inoculation of the soybean seed proved to be successful. The infection and N-fixing activity of the inoculant strains was satisfactory, resulting in an average of 6-7 composite, active nodules per plant. The dry mass of the plants increased by 25% in response to inoculation. The supplementary microelement solution did not lead to a significant increase in the dry mass of the plants or in the number of flowers. Only one of the strains used as inoculant was able to form efficient symbiosis with soybean, indicating that the host plant-microsymbiont relationship is extremely specific. This was confirmed by the PCR analysis.

The effect of 0, 30, 90 and 270 kg•ha-1 microelement loads on rape was investigated on a calcareous sandy soil in the region between the Danube and Tisza rivers. The salts of the microelements, in the form of Cr 2(SO4)3, K2Cr2O 7, CuSO4, Pb(NO3)2, Na 2SeO3 and ZnSO4, were applied on a single occasion at the start of the experiment in spring 1995. The four rates of six elements in three replications gave a total of 72 plots, each measuring 7×5 m = 35 m2. The growing site, which had the poor moisture regime characteristic of sandy soils, was prone to drought and poorly supplied with macroelements (NPK). The ploughed layer contained 0.7-1.0% humus and 2-3% CaCO3. The groundwater was located at a depth of 5-10 m. Basic fertilization with 100 kg each of N, P2O5 and K 2O per hectare was applied to the whole experiment every year. The main results were as follows: - In the course of the 10-month vegetation period, the winter rape crop received a total of 545 mm precipitation. Due to the dry weather in autumn and winter, the seed yield hardly reached 1 t•ha -1 and the by-product yield was 5 t•ha-1 on the untreated soil. In response to rising rates of Se the seed yield dropped significantly by 45% and the by-product yield by 22% compared with the control, when the carry-over effect was examined in the 7th year. The carry-over effect of the other elements was not significant. - On contaminated soil the maximum Cr concentration in the straw at harvest was 0.4 and 1.6 mg•kg-1 in the Cr(III) and Cr(VI) treatments, respectively. There was no significant Cr accumulation in the seed in either treatment. The Pb content reached 0.6 mg•kg-1 on soil severely loaded with lead, but in all cases the content in the seed was below the detection limit. The Cu content, too, increased hardly perceptibly in the seed, and the Zn content did not change as the Zn rate increased. In the by-products, however, the Cu and Zn contents both doubled. Selenium exhibited hyperaccumulation in both plant organs, with a concentration increase of two orders of magnitude, making the rape seed and the by-products unsuitable for human and animal consumption, respectively. - The quantity of Cr incorporated into the aboveground yield of rape at harvest amounted to 2.8 and 10 g•ha-1 in the Cr(III) and Cr(VI) treatments, respectively. The maximum uptake of Pb, Cu, Zn and Se was 3.6, 30, 109 and 1660 g•ha-1, respectively. Some 93% of the Se absorbed was accumulated in the by-products. The time required for the complete phytoremediation of soil contaminated with the 270 kg•ha-1 rate would be 163 years for Se, 2477 years for zinc, 9000 years for copper, 27,000 years for chromium Cr(VI) and 75,000 years for lead, assuming the same farming conditions. - On the untreated control soil the specific element content of 1 t seed + the associated by-products (kg•t-1) was 78 for N, 46 for P2O5, 96 for K2O, 158 for CaO and 27 for MgO. This is around twice the specific contents recommended by the Hungarian extension service for K2O and three times as high for CaO and MgO, partly due to the very wide by-product/main product ratio and partly as a consequence of the calcareous soil.

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