Abstract: Legume crops are able to fix atmospheric nitrogen by the symbiotic relation with specific bacteria, which allows the use of the mineral nitrogen-fertilizer to be reduced, or even excluded, resulting in more profit for the farmers and less pollution for the environment. Soybean (Glycine max (L.) Merrill) is one of the most important legumes with its high content of both protein and oil. However, it is recommended to combine the two nitrogen sources under stress conditions in order to overcome its negative effects. Drought stress is one of the most important abiotic stresses that increasingly limits soybean yields. A precise rate of mineral nitrogen under drought conditions is not confirmed, as it depends on many factors; soybean yield-potential and soil-nitrogen content to name a few. An experiment was conducted during 2017 growing season in Debrecen, Hungary to investigate the effects of nitrogen source on the physiology and the yield of the soybean cultivar 'Boglár'. Three N-fertilizer rates including no N-fertilizer (0 N), 35 kg ha-1 of N-fertilizer (35 N) and 105 kg ha-1 of N-fertilizer (105 N) were applied under three different irrigation regimes; severe drought stress (SD), moderate drought stress (MD) and control with no drought stress (ND). Half of the seeds in each treatment were pre-inoculated with Bradyrhizobium japonicum inoculant. The overall results showed significant differences associated with fertilization and irrigation, but not with inoculation. Increasing N rate was mostly accompanied with increased chlorophyll content and leaf area index, whereas it positively affected the plant height only when the drought was waived off. Plant height was the lowest under severe drought, regardless of inoculation and N-fertilizer application and rate. Inoculation increased the yield when there was no drought, and a low rate of N-fertilizer increased the yield furthermore; however, the high rate of N-fertilizer decreased the yield to a level even less than the inoculated control. On the other hand, the yield of non-inoculated plants increased as the N-fertilizer rate increased. Under drought conditions, adding N-fertilizer increased the yield of the non-inoculated plants compared to their inoculated counterparts; moreover, the high rate of N-fertilizer resulted in the best yield. Regardless of inoculation, the mean yield of the three fertilization rates was better when the water amount increased. It was concluded that applying N-fertilizer to provide the nitrogen needed by soybean plants, with the absence of N2-fixation process, is very important. Moreover, adding relatively high rate of N-fertilizer is very important under severe drought stress to alleviate the drought negative effects. Further research to recommend the best N-fertilizer rate to inoculated soybean under drought stress conditions should be executed.
Abstract: Biochar can be produced from the waste matter and its
application has been associated with returning of carbon in large
amounts into the soil. The impacts of this material on physical and
chemical properties of soil have been described. The biggest part of
the research work is dedicated to the hypothesis of this material’s
toxic effects on the soil life regarding its effect on the soil biological
component. At present, it has been worked on methods which could
eliminate these undesirable properties of biochar. One of the
possibilities is to mix biochar with organic material, such as compost,
or focusing on the natural processes acceleration in the soil. In the
experiment has been used as the addition of compost as well as the
elimination of toxic substances by promoting microbial activity in
aerated water environment. Biochar was aerated for 7 days in a
container with a volume of 20 l. This way modified biochar had six
times higher biomass production and reduce mineral nitrogen
leaching. Better results have been achieved by mixing biochar with
compost.
Abstract: Application of biochar to arable soils represents a new
approach to restore soil health and quality. Many studies reported the
positive effect of biochar application on soil fertility and
development of soil microbial community. Moreover biochar may
affect the soil water retention, but this effect has not been sufficiently
described yet. Therefore this study deals with the influence of
biochar application on: microbial activities in soil, availability of
mineral nitrogen in soil for microorganisms, mineral nitrogen
retention and plant production. To demonstrate the effect of biochar
addition on the above parameters, the pot experiment was realized.
As a model crop, Lactuca sativa L. was used and cultivated from
December 10th 2014 till March 22th 2015 in climate chamber in
thoroughly homogenized arable soil with and without addition of
biochar. Five variants of experiment (V1 – V5) with different regime
of irrigation were prepared. Variants V1 – V2 were fertilized by
mineral nitrogen, V3 – V4 by biochar and V5 was a control. The
significant differences were found only in plant production and
mineral nitrogen retention. The highest content of mineral nitrogen
in soil was detected in V1 and V2, about 250 % in comparison with
the other variants. The positive effect of biochar application on soil
fertility, mineral nitrogen availability was not found. On the other
hand results of plant production indicate the possible positive effect
of biochar application on soil water retention.
Abstract: Present work deals with the possible use of fertigation
in agriculture and its impact on the availability of mineral nitrogen
(Nmin) in topsoil and subsoil horizons. The aim of the present study is
to demonstrate the effect of the organic matter presence in fertigation
on microbial transformation and availability of mineral nitrogen
forms. The main investigation reason is the potential use of pretreated
waste water, as a source of organic carbon (Corg) and residual
nutrients (Nmin) for fertigation. Laboratory experiment has been
conducted to demonstrate the effect of the arable land fertilization
method on the Nmin availability in different depths of the soil with
the usage of model experimental containers filled with soil from
topsoil and podsoil horizons that were taken from the precise area.
Tufted hairgrass (Deschampsia caespitosa) has been chosen as a
model plant. The water source protection zone Brezova nad Svitavou
has been a research area where significant underground reservoirs of
drinking water of the highest quality are located. From the second
half of the last century local sources of drinking water show
nitrogenous compounds increase that get here almost only from
arable lands. Therefore, an attention of the following text focuses on
the fate of mineral nitrogen in the complex plant-soil. Research
results show that the fertigation application with Corg in a
combination with mineral fertilizer can reduce the amount of Nmin
leached from topsoil horizon of agricultural soils. In addition, some
plants biomass production reduces may occur.
Abstract: Compost can influence soil fertility and plant health. At the same time compost can play an important role in the nitrogen cycle and it can influence leaching of mineral nitrogen from soil to underground water.
This paper deals with the influence of compost addition and mineral nitrogen fertilizer on leaching of mineral nitrogen, nitrogen availability in microbial biomass and plant biomass production in the lysimetric experiment. Twenty one lysimeters were filed with topsoil and subsoil collected in the area of protection zone of underground source of drinking water - Březová nad Svitavou. The highest leaching of mineral nitrogen was detected in the variant fertilized only mineral nitrogen fertilizer (624.58 mg m-2), the lowest leaching was recorded in the variant with high addition of compost (315.51 mg m-2). On the other hand, losses of mineral nitrogen are not in connection with the losses of available form of nitrogen in microbial biomass. Because lost of mineral nitrogen was detected in variant with the least change in the availability of N in microbial biomass.
The leaching of mineral nitrogen, yields as well as the results concerning nitrogen availability from the first year of long term experiment suggest that compost can positive influence the leaching of nitrogen into underground water.
Abstract: Application of compost in agriculture is very desirable worldwide. In the Czech Republic, compost is the most often used to improve soil structure and increase the content of soil organic matter, but the effects of compost addition on the fate of mineral nitrogen are only scarcely described. This paper deals with possibility of using combined application of compost, mineral and organic fertilizers to reduce the leaching of mineral nitrogen from arable land. To demonstrate the effect of compost addition on leaching of mineral nitrogen, we performed the pot experiment. As a model crop, Lactuca sativa L. was used and cultivated for 35 days in climate chamber in thoroughly homogenized arable soil. Ten variants of the experiment were prepared; two control variants (pure arable soil and arable soil with added compost), four variants with different doses of mineral and organic fertilizers and four variants of the same doses of mineral and organic fertilizers with the addition of compos. The highest decrease of mineral nitrogen leaching was observed by the simultaneous applications of soluble humic substances and compost to soil samples, about 417% in comparison with the control variant. Application of these organic compounds also supported microbial activity and nitrogen immobilization documented by the highest soil respiration and by the highest value of the index of nitrogen availability. The production of plant biomass after this application was not the highest due to microbial competition for the nutrients in soil, but was 24% higher in comparison with the control variant. To support these promising results the experiment should be repeated in field conditions.
Abstract: This work presents the first results from the long-term laboratory experiment dealing with impact of drought on soil properties. Three groups of the treatment (A, B and C) with different regime of irrigation were prepared. The soil water content was maintained at 70 % of soil water holding capacity in group A, at 40 % in group B. In group C, soil water regime was maintained in the range of wilting point. Each group of the experiment was divided into three variants (A1 = B1, C1; A2 = B2, C2 etc.) with three repetitions: Variants A1 (B1, C1) were a controls without addition of another fertilizer. Variants A2 (B2, C2) were fertilized with mineral nitrogen fertilizer DAM 390 (0.140 Mg of N per ha) and variants A3 (B3, C3) contained 45 g of Cp per a pot.
The significant differences (ANOVA, P
Abstract: This work presents the first results from the long-term experiment, which is focused on the impact of intensive rainfall and long period of drought on microbial activities in soil. Fifteen lysimeters were prepared in the area of our interest. This area is a protection zone of underground source of drinking water. These lysimeters were filed with topsoil and subsoil collected in this area and divided into two groups. These groups differ in fertilization and amount of water received during the growing season. Amount of microbial biomass and leaching of mineral nitrogen and phosphates were chosen as main indicators of microbial activities in soil. Content of mineral nitrogen and phosphates was measured in soil solution, which was collected from each lysimeters. Amount of microbial biomass was determined in soil samples that were taken from the lysimeters before and after the long period of drought and intensive rainfall.
Abstract: Land degradation is of concern in many countries. People more and more must address the problems associated with the degradation of soil properties due to man. Increasingly, organic soil amendments, such as compost are being examined for their potential use in soil restoration and for preventing soil erosion. In the Czech Republic, compost is the most used to improve soil structure and increase the content of soil organic matter. Land reclamation / restoration is one of the ways to evaluate industrially produced compost because Czech farmers are not willing to use compost as organic fertilizer. The most common use of reclamation substrates in the Czech Republic is for the rehabilitation of landfills and contaminated sites.
This paper deals with the influence of reclamation substrates (RS) with different proportions of compost and sand on selected soil properties–chemical characteristics, nitrogen bioavailability, leaching of mineral nitrogen, respiration activity and plant biomass production. Chemical properties vary proportionally with addition of compost and sand to the control variant (topsoil). The highest differences between the variants were recorded in leaching of mineral nitrogen (varies from 1.36mg dm-3 in C to 9.09mg dm-3). Addition of compost to soil improves conditions for plant growth in comparison with soil alone. However, too high addition of compost may have adverse effects on plant growth. In addition, high proportion of compost increases leaching of mineral N. Therefore, mixture of 70% of soil with 10% of compost and 20% of sand may be recommended as optimal composition of RS.