Abstract of Revised

THE INVESTIGATION OF EFFECT OF CULTURE HISTORY ON POTASSIUM IN SOILS UNDER SUGARCANE CROP IN KHUZESTAN PROVINCE OF IRAN

A.A, Bostani , GH.Savaghebi

Respectively Ph.D Student & Assistant Professor of Dept. Soil Sci. Agri. Faculty of Tehran University. Tehran. IRAN

ABSTRACT:
IN ORDER TO INVESTIGATING THE EFFECT OF CULTURE HISTORY ON AVAILABLE K IN SOILS UNDER SUGARCANE CULTIVATION IN KHUZESTAN PROVINCE, 48 COMPLEX SOIL SAMPLES WERE COLLECTED FROM DEPTHS OF 0-30 AND 30-60CM. RESULTS INDICATE THAT IN FARMS WITH LONG-TERM CULTURE AVAILABLE K IS LOWER THAN REPORTED CRITICAL LEVELS. WHEN TESTING THE EFFECT OF CULTURE HISTORY ON AVAILABLE K IN THE 30CM DEPTH WE OBSERVED THE CULTURE HISTORY HAS DECREASED AVAILABLE K OF THESE SOILS (P < 0.05). THIS CORRELATION WAS NOT SIGNIFICANT FOR DEPTH OF 30-60CM. THE INVESTIGATING OF MEAN YIELD IN FARMLANDS OF KARUN CULTURE AND INDUSTRY (24000HA) OVER 19 YEARS (1982-2001) INDICATED THAT WITH INCREASING CULTURE HISTORY THE DIFFERENT BETWEEN PLANT AND RATON HAS BEEN INCREASED (R=0.71).


Key words: Potassium , sugarcane, Culture history, Iran


Potassium Plays A Key role in plant physiology and any deficiency of these element causes irretrievable injuries in plant growth and reduces the quality and quantity of yield. Sugarcane is not exception from this role and likewise absorbs K from soil more than other elements [4]. Sufficient supply of K not only increases cane yield but also has significant effect in quality of productive sugar [1]. Sing et al [5] with adding different levels of K to soils under sugarcane in India resulted that the increase of 50Kg(k2o)/ha caused significant increase in sugarcane yield. Tioary et al [6] with studying effect of K on cane yield and sacarose percentage resulted that applying 60Kg(k2o)/ha to the soils that their available K is 402 Kg /ha (a.k= 134PPM) caused significant increase in cane yield and sacarose percentage (p=0.05). Jafarinezhad [1] with investigating effect of K on sugarcane in soils under sugarcane in Khuzestan resulted that applying K- fertilizers has caused increase of quality of sugarcane yield (purity and sacarose percentage) and increased sugar produced per hetear. All of entwined literatures are indicative the importance of this element and therefor investigating of K status and identifying its critical level has specific importance. Some investigators have studied critical level of available K for sugarcane. Zambellow and Orlando filho [3] suggested that critical level of available K for soils under sugarcane in South Africa is 112 µg/gr. soil (extracted by OACNH4). Morberdly [3] mentioned that identifying of critical level of available K is related to textural class of soil and reported that the critical level of available K for sugarcane in silos with more than 40% clay is 200µg/gr.soil. In the areas under sugarcane in Khuzestan due to high level of K in soils under sugarcane the level of available K in initiative years of sugarcane Cultivation in the soil was sufficient and no K fertilizer had been added the soil. But the clay minerals in these soils were not permanent source of K in these soils and the level of releasing of unavailable K has been decreased during time (due to increasing of adsorption energy). In recent years the yield of sugarcane has been decreased about 25 to/ha, but there is no clear reason for this problem. The propose of this study was investigating of status of available-K and effect of culture History on this part of K in soils under sugarcane in Khuzestan.

Methods and Materials:

In this filed, 48 complex soil samples from farmlands of Karun culture and industry and Haft Tappeh in the orders 24 pairs from depths of 0-30 and 30 – 60 cm were Collected. Soil sample was performed with this presumption that the clay percentage and culture History have a extent range. Physical and chemical properties of soil sample including soil texture(hydrometer method), pH (saturated extract), CEC (Bower), %Organic Carbon (wolkely & blak), soluble K (in saturated extract), and available K (Extracted by OACNH4) were determined. Some statistical parameters related to physical and chemical properties of these soils are given in table [1].

Table 1: some statistical parameters of physical and chemical properties of soil


In order to investigate the effect of culture History on available K , making control over other factors that may affect available K is necessary. With presumption that the type of clay, CEC, and %OM are properties of soil that affect available K and with regarding that the clay mineralogy of soils of study area is constant and mostly cholorite, smectite and illite and whit regarding that we can assume CEC is parameter that is representative of clay percentage and OM. In order to dominating other parameters effective on available K and finally investigating the effect of culture History on this part of K, the levels of measured available K are divided to CEC and results are considered as an index. In order to investigating effect of culture History on available K, soils with respect to culture History classified to 6 group including <17, 20, 23, 26, 30 and 41 years culture History and finally the effect of culture History on available k was investigated.

Result and discussion:
1. According to the table 1 and regarding that critical level of available K for sugarcane is different but its reported average level is 120 mg.K g-1soil, the levels of available K in these area are lower thane critical level necessary to sugarcane and probably this is one of factors that cause decrease of sugarcane yield in recent years.
2. With testing effect of culture History on available K in depth of 0-30 cm, we observed that culture History had decreased available K in these soils (p < 0.05). This correlation was not significant for 30-60 cm. It seems that the reason of this fiddling is that approximately 70% active roots of sugarcane are extending in depth of 0-30cm.
3. Investigating of means yield in farmlands of Karun culture and Industry (24000 ha) during 19 years (1982 – 2001) indicated that, with increasing culture History, differences between plant and Raton have been increased (r = 0.***). According to the graph 1 probably one of important factors that causing this situation is condition of available K in soil. In first years of Cultivation the level of available K was to the extent that had satisfied Plant and Raton. With increase culture History the level of available k has decreased but before of planting, soil had been under following condition for14 months. Under these condition according concentration gradient resulted in soil, K has been released from nonexchangaeble sites and becomes as exchangeable and soluble K (forms available for plant) and finally has been used by plant. But in Raton, there is no such opportunity for K in order to release from nonexchangeable sits according concentration gradient and become to exchangeable and soluble K (form available for plant) and use by Raton.
4. According to the graph [1], resulted from correlation between available K index ( K exchangeable/CEC) and culture History we can understand that in primitive years of farming due to low energy of adsorption necessary for absorbing of K, roots of plant have ability of adsorption of K from exchangeable sits and as a result the decrease of K with respect to time is high. But with increasing of culture History (30 – 41 years) due to increasing adsorption energy, plant has not enough energy for adsorption of K from exchangeable site and as a result the intensity of decrease of available K has decreased and finally the yield has decreased with high intensity.
Refrences

[1]- Jafarinezhad. A, 1998, Investigation Effects of Potassium and Micronutrients on quality and quantity yield of Sugarcane in Khuzestan Province. M.Sc thesis’s of Soil Science. Agriculture faculty, Tarbiat Modarres, University of Tehran.Iran

[2]- Sharply,A,N. 1990.Reaction of fertilizer Potassium in soils of differing mineralogy. Soil Sci.149: 44 -51
[3]- Filho, J.O.1985, Potassium nutrition of sugarcane, IN: R.D. Munson, 1985.Potassium in Agriculture. American Society of Agronomy and Soil Science Society of American Medison WI, USA
[4]- Martin, R. 1993. Soil Sampling and of Analysis. Canadian Society of Soil Science. LEWIS Pub.
[5]- Wild, A. 1988.Potassium, sodium, calcium, magnesium, sulfur,silicon.IN:Wild,A.1988. Rusell,s soil conditions & plant growth. 11ed. John wiley & sons ,inc.Newyor
[6]- Singh K.D.N. et al.1992. Effect Of Potassium on Yield and Quality of Sugarcane on Calciorthent under Drought Condition. J.Indian Soc. Soil Sci. Vol. 40: 105-110.
[7]- Tiwarl R.J. et al. 1998. Response of Sugarcane to Levels and Time of Application of Potassium. J.Indian Soc. Soil Sci. Vol. 46 No 2: 319-322.