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Evaluation of the correlation between SPAD readings and absolute chlorophyll content of maize under different nitrogen supply conditions
121-126Views:324Currently, one of the most important objectives of agriculture is to maintain the principles of the sustainability. The use of precision technologies in agriculture belongs to this topic. The use of precision technologies is increasingly widespread in the cultivation of various agricultural crops, including maize. Sensing is an important part of these techniques. In our experiment we compared two methods: measuring relative chlorophyll content and the method of determine the extractable chlorophylls. The experimental plant was maize (Zea mays L.) and the measurements were performed at an early development stage (V8) of three genotypes. Three levels of nitrogen (0; 80; 160 kg ha-1) were applied during the experiment. The relative chlorophyll content was measured by SPAD-502 (Minolta, Japan) and a handheld GreenSeeker (Trimble, USA) device. The extractable total chlorophyll content decreased in parallel with the increased nitrogen level. The obtained SPAD values were diversified furthermore the NDVI values have not been changed for the effect of different nitrogen fertilization. In the early stages of development of maize, these parameters need to be complemented with other measurements to provide reliable information about the crops nitrogen status.
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Nitrogen Content of Hungarian Soils and Nitrogen Fertilization
51-61Views:90For crop production and agricultural production, the most important natural resource is the soil that can optionally renew. Paralelly with this, soil plays a major role in the geological and biological cycle of elements. As a result of the big (geological) and small (biological) element cycles, the elements and combines neccessary for organisms can accumulate in the soil creating suitable living conditions for plants and other organisms. Soil is a heterogenous system both horizontally and vertically, and soil constituents show great variety in all the three dimensions, in addition, most of the parameters can also change between two examination dates. When talking about the factors influencing plant production, one should take into account this variation and heterogenity in time and space. When making fertilization recommendations, these factors should all be considered. In any consultation system, most of the mistakes and errors made are due to the unsatisfying soil testing and the negligence of soil heterogenity. In the practice of fertilization the biggest mistake is the improper soil sampling, then comes the methodical mistake of soil testing, which is followed by the inaccuracy of instrumental analysis and the subjectivity of result evaluation, but the latter two are negligible compared to the others. Under normal, i.e. production conditions, the quantity and distribution of nutrients in the soil are greatly dependent upon the applied technology, the amount and form of the applied natural and artificial fertilizers and the quality of fertilization.
Fertilization recommendations are needed because in the layer which is accessible for plant roots only a part of the nutrient content is available for plants in a specific production cycle. An illustration of this is that though the upper 1 m layer of an average chernozem soil contains more than 5000 kg N, 12000 kg K2O and 1500 kg P2O5 (form of expression mostly used in Hungary), the application of fertilizer doses which are just fractions of these quantities is essential. This is due to the fact that the available amount of the total nutrient content depends from the quality of soil, the environmental factors (the physical and chemical qualities of the soil) and the specific nutrient’s qualities (solubility, adsorption). Knowledge of these processes and the examination of the factors influencing the actual nutrient content are vital for working out a fertilization practice, which does not put more strain on the environment than neccessary.All of the above mentioned should be considered when applying inputs in the fields. In a well-functioning practice that considers the economic and environmental conditions (unfortunately the present production and economic conditions do not enable an appropriate level and degree), three nutrients are supplemented generally (and were supplemented in the last decades): nitrogen, phosphorus, potassium.
Studying the nutrient balance of the Hungarian field production’s last hundred years, we can draw some interesting conclusions.
The nutrient balance became positive for nitrogen and potassium in the second half of the 1960’s, while for phosphorus it was positive from the first half of the 1960’s and this period lasted until the end of the 1980’s.
Neither before the 1960’s, nor since the 1990’s has the amount of nutrients supplemented in a specific year reached the amount of the nutrient uptake of the same year. -
Energy crops on less favoured (alkaline) soil
115-118Views:99The reduction in fossil energy and row material sources induces growing demand for renewable resources. The growing demand for herbal raw materials has land use impacts as well. One way to reduce the conflict between the food and energy crops can be the utilization of less favored areas by growing energy crops. Among the potentially available areas for this purpose the salt affected soils (SAS) occupy a significant territories. SAS with structural B-horizon (meadow solonetz soils) represent the most wide spread group of SAS in Hungary. About half of these soils have been reclaimed and used as arable land and the remaining 50% are used as grassland. Sweet sorghum production for manufacturing of alcohol production was investigated in a long term amelioration and fertilization experiment on a salt affected soil (meadow solonetz). By means of regression analyzes the effect of sodium content of the soil and increasing mineral fertilizer doses were studied. According to the multiple regression analysis only the effect of nitrogen fertilizer was significant. On the solonetz type salt affected soil the effect of water soluble salt content of the soil was not significant, but there was a closer correlation between the ammonium-lactate sodium content and the yield of sweet sorghum. The maximum green mass was 45–50 t ha-1, in the case of low Na content and high level of nitrogen fertilization.
In order to quantify the potential yield of natural grass vegetation the relationship between the soil forming processes and the grass vegetation
was investigated. Beyond the different forms of Na-accumulation, the spatial pattern (mosaic-like characteristic) is also an inseparable feature of salt affected soils. The difference in the water regime, caused by the micro-relief is the main cause of variability. The run-on water keeps the deeper parts of the catena position wet longer. The wet situation causes more intensive leaching. In the low-laying parts of salt affected soils species preferring wet situations (mainly Alopecurus pratensis) are in majority. On the higher parts of the micro-relief species tolerating dry situations (mainly Festuca pseudovina) are dominant. The yearly grass production of low laying areas can be 4–7 t ha-1 but because of prolonged wet conditions the grass is not grazed and mowing can only be in old state. This old grass is not proper for feeding, but it may be suitable as energy plant. -
Impact of nitrogen and sulphur fertilization on the growth and micronutrient content of spring wheat (Triticum aestivum L.)
211-219Views:166Micronutrients are as important as macronutrients for crops. Each micronutrient has its own function in plant growth. Zinc is important for membrane integrity and phytochrome activities. Copper is an essential micronutrient required for the growth of wheat. Manganese is required for enzyme activation, in electron transport, and in disease resistance. The pot experiment was set up in greenhouse on calcareous chernozem soil Debrecen-Látókép with a spring wheat. In certain development stages (according to BBCH growth scale of wheat), at the beginning of stem elongation (29–30), at the heading (51–59), at the flowering (61–69) stage three average plants were removed from all pots for analysis. Fresh and dry weight of the plant samples were measured. Plant leaves after drying were digested by HNO3-H2O2 methods and manganese, zinc and copper contents of plant were quantified by atomic absorption spectrophotometry. At the flowering stage, when the nutrient uptake of plants is the most intensive, the weight of wheat ranged between 0.94–1.57 g plant-1. In this development stage, the NS2 treatment produced the highest weight of wheat, and compared to this the NS3 treatment decreased that value already. The results show unfavourable effect of NS3 treatment. On the basis of microelement content of wheat and the weight of a plant, nutrient uptake by plant were calculated. At the beginning of growth the starter treatment had positive effect on Cu-uptake compared to the NS1 treatment, where the same dose of fertilizer was stirred into the soil. Wheat is very sensitive to copper deficiency, so copper dissolved by starter treatment could be favourable to the early development of wheat. At flowering stage the Zn-uptake of wheat became the highest and it was between 133.7–234.6 mg plant-1. The Mn-uptake of wheat plant was higher than the Cu- and Zn-uptake of wheat.
This phenomenon can be explained by the fact that the untreated soil had higher Mn-content, than Cu- and Zn-content. To summarize the results, it can be stated, that the copper uptake of wheat was more affected by the different treatments in the stage of stem elongation, while Mn- and Zn-uptake of wheat were influenced primarily in the stage of heading and flowering.
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The effect of sulphur and nitrogen supply on the growth and nutrient content of spring wheat (Triticum aestivum L.)
65-70Views:194Sulphur is an essential element for plants. Decreasing sulphur deposition from the air, and the use of more concentrated phosphate fertilizers, which contain no sulphur, has led to reports of sulphur deficiencies for wheat. Sulphur deficiency significantly affects yield and also the quality of wheat. The pot experiment was set up on calcareous chernozem soil at Látókép, Hungary, test plant was spring wheat (Triticum aestivum L). Seven treatments were used where nitrogen and sulphur were supplied as soil fertilizers in increasing rates (NS1, NS2, NS3) and in foliar fertilizer as well (NS1+fol., NS2+fol., NS3+fol.). Plant aboveground biomass production was determined in samples taken in the stages of development BBCH 29-30, 51-59, 61-69, 89. The nitrogen and sulphur content of straw and grain were measured. N/S ratios of grain and straw were calculated. The weights of grain were ranging between 8.6–16.1 g/pot. NS2 and NS2+fol. treatments produced the highest values. Foliar fertilizer had no further effect on grain. Analysing the values of the straw, it was observed that tendencies were similar to values of grain. The NS2 treatment produced the highest weight of straw and the NS3 rate already decreased that amount. The obtained results show the unfavourable effect of excessively high rate applied in NS3 treatment. The supplementary foliar fertilizer had no significant influence on the weight of straw. Both N and S-uptake of plant was very intensive at the stem elongation stage, then the N and S-content of plant continuously decreased in time in all treatments. The N-content of grain ranged between 2.215–2.838%.The N-content of grain slightly increased with increasing of nitrogen doses. In the higher doses (NS2, NS3) foliar fertilization slightly increased the nitrogen content of grain, although this effect was not statistically proved. The N-content of straw varied from 0.361 to 0.605%. The growing dose of soil fertilizer also considerably increased the nitrogen content of straw. Foliar fertilization further increased the nitrogen content of straw. The S-content of grain ranged between 0.174–0.266%. The lowest fertilizer dose (NS1) significantly increased the sulphur content of grain. The further increasing fertilizer doses (NS2, NS3) did not cause additional enhance in sulphur content of grain.The foliar fertilizer also did not change the sulphur value of plant. The increasing amount of soil fertilizer and the supplementary foliar fertilizer had no effect on the sulphur content of straw. The treatments influenced the N/S ratios of grain and straw. On the basis of experimental results it can be concluded that the examined nitrogen and sulphur containing soil fertilizer had positive effect on the growth and yield of spring wheat grown on the calcareous chernozem soil. The soil fertilizer application enhanced the grain nitrogen and sulphur content. The highest rate of fertilizer (600 kg ha-1) proved to have decreasing effect on the yield. The sulphur and nitrogen containing foliar fertilizer did not have significant effect on the yield parameters but slightly increased the nitrogen content of plant.