|
|
| Bildiri Özetleri | |
| Ana Sayfaya Dönüş |
| ISD Ana Sayfası |
|
Cihat Kütük, Gökhan Çayci, Abdullah Baran, Oğuz Başkan Soil Science Department, Agricultural Faculty, Ankara University, 06110- Ankara Turkey ABSTRACT In this research, effect of humic acid and incubation period on some soil properties were determined. Liquid humic acid was used in the research. Seven rates of humic acid (0, 100, 250, 500, 1000, 2000 and 4000 ppm) were added to the soil at three incubation periods (30, 60 and 90 days). At the end of the each incubation period, the changes in some physical and chemical soil properties were determined. Generally, humic acid (HA) addition decreased pH values at the first incubation period. EC values were increased depending on humic acid rates at the all incubation periods. It was seen that the effect of HA on available Fe, Mn and Zn contents of the soil were more clear above 500 ppm rates of HA. Available Fe, Mn and Zn contents of the soil were found higher at first incubation period than in other periods. The amount of water stable aggregates were found higher than the control at rates of 2000 and 4000 ppm of HA. INTRODUCTION The effect of organic matter on soil properties such as physical, chemical and biological is well known for a long time. The organic matter content of soils in Turkey is, generally, low (Eyüpoğlu 1998). Soil organic matter contains residues of plants and animals and primary and high polymer organic compounds decomposing from them. Soil organic matter has not certain chemical formula due to its dynamic structure. Soil organic matter are mainly consists of humic and fulvic acids which called humin materials (Schinitzer 1982; Andriesse 1988). They are mainly produced from nitrogenous compounds containing decomposed amino acids and aromatic complexes(Andriesse 1988). Those organic complexes affect soil properties and physiological properties of plant due to carboxyl (-COOH) and phenolic (-OH) groups (Lee and Barlett 1976; Schinitzer 1992). It was reported that humic acid affects physical and chemical properties of soils (Vaughan and Linehan 1976; Boyle et al. 1989; Schinitzer 1992). However, their effects on soil have not already been clearly concluded. The aim of this study was to determine the effect of humic acid used commercially on water stable aggregates, pH and EC and availability of some micro nutrients. MATERIALS & METHODS Soil sample used in the study was taken from depth of 0-20 cm in Agricultural Faculty Research Area. Humic acid used, extracted from leonardite, contains at the rate of 9.5 % humic acid. Soils were sieved through 0-2 mm and filled into 400 cm3 volume of plastic pots. Soil were brought to 70 % of field capacity. Humic acids were added to each pots at the rates of 0, 100, 250, 500, 1000, 2000 and 4000 ppm, then, incubated at 25 °C during 30, 60 and 90 days. Properties of the materials used in the research were given in Table 1.  Texture (Bouyoucos 1951), pH and electrical conductivity (EC) (U.S. Salinity Lab. Staff 1954), lime (Çağlar 1958), organic carbon (Jackson 1962), water stable aggregates (Kemper 1965), field capacity and wilting point (U.S. Salinity lab. Staff 1954) and available Fe, Mn, Zn and Cu (Lindsay and Norvell 1969) were determined. Statistical analyses were evaluated by ANOVA and differences among the groups were separated by LSD. DISCUSSIONS Changes in pH and EC values of soils were given in Table 2.  Where differences in pH values depending on incubation periods and rates of HA were noticed. pH values were decreased partially due to incubation periods. However, that decreasing is not regular when we consider the humic acid rates. Especially, pH values significantly decreased in 90th days with respect to the other incubation periods. Where no differences in EC values depending on both incubation periods and humic acid rates were noticed, except 2000 and 4000 ppm of humic acid rates. EC values in 2000 and 4000 ppm of HA were higher than in the other rates of HA. Humic acid, occurring complexes with metallic ions related to carboxyl(-COOH) and phenolic(-OH) groups in its structure, supplies nutrients to the soil (Schinitzer 1992). These complexes being non water-soluble forms, prevent leaching of the metallic ions from the soil, as a result growth medium enrich for those plant nutrients. Andriesse (1988) has reported that efficiency of humic acid on uptakes of nutrients in the mineral soils is more considerable than the organic soils. However, many scientist emphasised that adding of humic acid to the mineral and organic soils improve plant growth and uptake of some micro nutrients. As shown in Table 3, the highest available Fe contents were determined at the first incubation period. Available Fe contents of the soil samples were higher at the first incubation period than the other periods depending on humic acid rates and incubation periods. Especially over 500 ppm rates of humic acid were more efficient on availability of Fe. Garcia et al (1995) reported that iron-humic complexes under adverse soil conditions supply Fe to the soils and stimulate to the plant growth. These results are consistent with the findings of Barnard et al (1992). Manganese ad Zinc contents of the soils changed with humic acid rates and incubation periods (Table 4 and 5). Available Mn contents of the samples were significantly increased at the first incubation period. However, Mn and Zn contents of the samples were lower in the other incubation periods.    As shown in Table 6, Cu contents of the soils changed irregularly. Attraction order of metals is reported as Cu>Pb>Zn>Ni>Co>Mn>Ca>Ba (Andriesse 1988). For this reason, Cu and Zn can be more easily bound by the organic components than the other metals. Therefore, their availability will be less than the others.  In this research, it was determined that the availability of both Fe and Mn can be significantly decreased within the time depending on humic acid rates and incubation periods. These situation shows that applying of humic acid within a few times during the plant growth will be more suitable for plant yield. As a conclusion, although 1000 ppm rate of humic acid was found more suitable dose with related to availability of micro nutrients and economical reasons, it should be considered that application rate of HA can change with environmental conditions. Water stable aggregates of the soil were affected by the humic acid rates and incubation periods (Table 7).  Water stable aggregates of the control sample in the first incubation period was highest (36.84). Visser and Cailier (1988) have reported that low concentrations of humic acid cause in dispersion of soil particles, and high concentrations of humic acid cause to flocculation in humic glayey soils. Water stable aggregates decreased in the third incubation period in all humic acid rates comparing to other incubation periods. A relative decreasing was observed in the second incubation period. It was well known that soil organic matter, especially, humic materials are cementing agents in soil particles, however, certain organic components can play a role paradoxically as a dispersion element in clay-water systems (Tarchitzky et al. 1993). Shanmuganathan and Oades (1983) have reported that addition of anions to soils cause to dispersion in clay fraction associated with decreasing isoelectric point, and it is known that fulvic acids especially, are the most efficient anions. REFERENCES Andriesse, J.P. (1988). Nature and management of tropical peat soils. FAO Soils Bulletin No. 59, 165. Eyüpoğlu, F. (1998). Türkiye topraklarının verimlilik durumu. Toprak-Gübre Araştırma Enst.Yay. Genel Yayın no.220. Barnard, R.O., Van der Watt, H. H., Dekker, J., Cronge, I., Mentz, W. H., Cillie, G.E.B., Laker, M.C. (1992). Application of Fe and Zn to lime-rich soils in the form of formulated coal products. Science of the Total Environment, 117 / 118, 569 - 574. Bouyoucos, G.J. (1951). A recalibration of the hydrometer method for making mechanical analysis of the soil. Agronomy Journal (9): 434-438. Boyle, M., Frakenburger, W.T.Jr., Stolyz, L.H. (1989). The influence of organic matter on soil aggregation and water infiltration. Journal of Production Agriculture. 2: 4, 290 - 299. Çağlar, K.Ö. (1958). Toprak ilmi. Ank.Üniv.Zir.Fak. Yayınları, 241. Garcia, M.J.M., Sanchez, D.M., Iniguez, J., Abadia, J. (1995). The ability of several iron (II)-humic complexes to provide available iron to plants under adverse soil conditions. Iron Nutrition in soils and Plants. Proc. of the 7th Int. Sypm. on Iron Nutrition and Interactions in Plants, Zaragoza-Spain, 27 June-July, 1995, 235-239; Developments in Plant and Soil Sciences Vol 59. Jackson, M.L., (1962). Soil chemical analysis. Prentice Hall Inc. Eng., Englewood Cliffs. N.J. Kemper, W.D. 1965. Aggregate stability. In: Methods of Soil Analysis, Part I. (Black C. A., ed.) Am. Soc. of Agr. Inc., Madison, Wisconsin, 511-519. Lee, Y.S., Bartlett, R.J. (1976). Stimulation of plant growth by humic substances. Soil Sci. Soc. Am. J., 40:876-879. Lindsay, W.L., Norwell, W.A. (1969). Development of a DTPA micro-nutrient soil test. Soil Sci. Amer. Proc. 35: 600-602. Shanmuganathan, R.T., Oades, J.M. (1983). Influence of anions on dispersion and physical properties of the A horizon of a red-brown earth. Geoderma. 29, 257-259. Schnitzer, M. (1982). Organic matter characterisation. In: Methods of Soil analysis. Part 2. (eds: A.L.Page, R.H.Miller and D.R. Keeney) Soil Science Society of America Madison, WI, 581-594. Schnitzer, M. (1992). Significance of soil organic matter in soil formation, transport processes in soils and in the formation of soil structure. Soil Utilization and Soil Fertility. Volume 4, Humus budget, 206, 63-81. Tarchitzky, J., Chen, Y., Banin, A. (1993). Humic substances and pH effects on sodium-and calcium-montmorillonite flocculation and dispersion. Soil Sci. Soc. Am. J. 57, 367-372. Vaughan, D., Linehan, D.J. (1976). The growth of wheat plants in humic acid solutions under axenic conditions. Plant and Soil, 44, 445-449. Visser, S.A., Caillier, M. (1988). Observations on the dispersion and aggregation of clays by humic substances: I. Dispersive effects of humic acids. Geoderma. 42, 331-337. U.S. Salinity Lab. Staff. (1954). Diagnosis and improvement of saline and alkali soils. USDA, Handbook No.60, Washington, D.C. 160. |