Impact of Wastewater Irrigation on Nutrients Uptake by Crops

Impact of Wastewater Irrigation on Nutrients Uptake by Crops

Thippeswamy H. N.

Principal, T.John Institute of Tech

Bangalore 560083 India.

Manjunath N.T.

Professor and Director Centre for Env. Sci. Engg& Tech

University BDT College of Engg., Davangere 577004.India.

Abstract :Reusing of industrial effluents for irrigation may not only solve the disposal problem, but also serves as an additional source of liquid fertilizer providing all the macro and micro nutrients needed for the crops growth. Nevertheless, accumulation of metals and nutrients on land receiving these wastewaters and uptake by the crops are of public concern, because of possibilities of their entry into the food chain. Therefore indepth studies/care is required to be taken before recommending the usage of industrial effluents for irrigation. The impact of sugar mill effluent and its diluted combination with sewage along with control irrigation (water) on uptake of nutrients by crops (Radish, Palak and Maize) are discussed in this paper. The type of soil was found to have no bearing on the uptake of nutrients by the crops,within the statistical limitations. However the nutrient uptake was found to be a function of type of a crop.

Key words : Sugar mill effluent, Nutrients, Radish, Palak, Maize.

INTRODUCTION:

The demand for fresh water has been rising in response to industrial development, increased reliance on irrigated agriculture, massive urbanization and rising living standards on one hand and on the other hand availability of fresh water to humanity is shrinking. At the same time with population expanding at a high rate, the need for increased food production and thereby increased water requirement for irrigation is apparent. Further, rapidly increasing industrialization has resulted into the generation of huge quantity of wastewater, many of which found to contain nutrients and also free from toxicants. Safe disposal of these wastewaters has become a challenge for industrial managers and scientists.

Thus caught between finite and increasingly polluted water supplies on one hand and rapidly rising demand on the other, the need for alternative water resources especially for irrigation is gaining attention.Under this situation alternative method of augmenting assumes importance. One such method is the use of industrial effluents for agriculture which assured paramount importance in recent years. Properly planned reuse of industrial effluents for irrigation leads to solve the surface

water pollution problem and not only conserves valuable water resources but also takes advantage of nutrients contained in it, which might reduce or even overcome the requirements of commercial fertilizers. Many countries have included wastewater reuse as an important dimension of water resources plan.

Many researchers have carriedout studies to evaluate the feasibility of reusing wastewaters for irrigation (Ashok &Musarrat : 2002, Baruah and Das : 1998, Patel et.al : 2003, Singh et.al: 2003, Velu et.al : 1999, Rekha et.al

: 2003). These studies emphasized that, there has to be sound planning and careful management to ensure that the quality and the quantity of available wastewater is put to the best use and potential problem related to the use of such wastewaters is prevented. Moreover the problems and solutions are site, crop and effluent specific and there are still many problems worthy of investigation. Uptake of nutrients by crops which are very much needed for their growth and survival is a phenomenon behaviour of the crops. Eventhough, the best nutrient content in the crops is needed for better health conditions of consumers, their content beyond certain limits may be toxic to human beings. This paper throws light on results of experimentation carried out to evaluate the impact of sugar mill effluent and its diluted combination with sewage on uptake of nutrients by crops.

MATERIALS &METHODOLOGY:

Pot experiments were conducted under natural atmospheric conditions to simulate actual field conditions using circular pots made of RCC, each of diameter 600 mm and depth 320mm. Effluent collected from nearby sugar mill, sewage from nearby drain and water from borewell existing in the institution campus were analysed as per standard methods (APHA:1991) and were used for experimentation. Three soils of different classes were collected from nearby agricultural fields and the soil type identification tests were conducted and were classified using guidelines given in SP36 Part II. The soils were analysed for various characteristics as per standard methods. The

effluent was applied at regular intervals based on wilting condition of the crops and until the soil was saturated. The seeds of Radish, Palak and Maize were collected form recognized agricultural outlets and were used for experimentation. To assess the accumulation of nutrients in crops on long term application of wastewater for irrigation, pot experiments were conducted under specified conditions 3 times (3 cycles). On harvesting the crops were analysed for their nutrient contents.

The following wastewater combinations were tried

• Irrigation with borewell water (control) T1

• Irrigation with sugar mill wastewater (SMWW) T2

• Irrigation with SMWW + Sewage (1:1) T3 RESULTS AND DISCUSSIONS:

Table-1 through light on characteristics of wastewater combinations used for experimentation. The characteristics of soils used for experimentation are summarized in Table-2. Wastewater combinations indicated the acidic nature. The soils pH being more than that of wastewater combinations has been recorded. T3 exhibited much higher concentration of TDS compared to T1 and T2. The SHWW was found to be rich in organic content (BOD : 910 mg/l) followed by T3 (BOD : 500 mg/l) whereas phosphate and potassium contents were not detected in the SMWW. On the other hand wastewaters combinations (T3) was found to contain phosphate and potassium concentration of 4.65 mg/l and 9.33 mg/l respectively. Total nitrogen content in treatment options T1, T2 and T3 were respectively 0.2 mg/l, 27.3 mg/l and 18.83 mg/l.

Accumulation of Nitrogen, Potassium and Phosphorous in crops on harvesting (cycle-III) under varied experimental conditions are shown in figs.1, 2 and 3.

The observations recorded revealed that the type of soil has got no bearing on the uptake of nutrients by the crops within the statistical limitations of the study. Further within the statistical limitations of the study, the concentration of nutrients in wastewaters adopted for experimentation was found to have least influence on uptake of nutrients by crops. However, the nutrient uptake was found to be a function of type of a crop. Maximum and minimum uptake by Radish and Maize respectively were recorded. Increase in trends of accumulation of nutrients from cycle I to III of crops have been noticed. Comparison of different nutrients by a particular crop with type of soil could not be made because of high variations on their concentration both in soils and waster combinations. The variation is uptake of Nitrogen, Phosphorous and Potassium ranging from 0.10 to 0.26 mg/l, 14.5 to 19.3 mg/l and 26.7 to 30.8 mg/l respectively by radish grown in all the soils with different treatment options tried were recorded. These

values in maize were respectively 0.04 to 0.11 mg/l, 3.3 to

5.9 mg/l and 8.2 to 10.5 mg/l.

CONCLUSIONS:

The analysis of results of nutrient uptake by crops lead to a conclusion that nutrient uptake by the crops is independent of soil type and initial concentraion of nutrients in wastewaters but uptake is a characteristic function of particular crop. Root crops were found to be more susceptible and grained crops are least susceptible for nutrient uptake. The studies revealed the increase in trends of accumulation of nutrients with repeated cultivation of crops.

REFERENCES:

1. APHA. Standard Methods for the Examination of Water and Wastewater. 18th Edition. American Public Health Association. New York, 1991.

2. Ashok B.T. and Musarrat J. Mechanical, Physico-Chemical and Microbial Analysis of Oil Refinery Waste Receiving Agricultural Soil. Indian J. Environ. Health. Vol.44. No.4. October 2002.

3. Baruah B.K. and Das M. Study on the Impact of Paper Mill Effluent on Germination Behaviour and Seeding Growth of Crop Plant. OryzaSativa. L. Poll Res. 17(1). pp:65-68, 1998.

4. Bureau of Indian Standards. Guidelines for Quality of Irrigation Waters. IS: 11624, 1986.

5. Bureau of Indian Standards. Soil type identification tests and guidelines : SP 36 Part-II, 1986.

6. Hayat S., Iqbal Ahmad Z.M., Azma A., Ahmad Inam A. and Samiullah. Long-term effect of Oil Refinery Wastewater on Crops Yield, Heavy Metal Accumulation in Soil and Crop Produce. Poll. Res 21(3). pp:297-303, 2002.

7. Patel K.P., Pandya R.R., Maliwal G.L., Patel K.C. and Ramani V.P. Suitability of Industrial Effluents for Irrigation around Bharuch and Ankleshwar Industrial Zone in Gujarat. Poll Res. 22 (2). pp:241-245, 2003.

8. RekhaThakre, DeshabRatar P.B. and Nanoti M.V. Management of Industrial Effluent for Crop Productivity. Int. Conf. on Water Quality Management held on 13th 15th Feb.2003. New Delhi. India,

9. Singh V.K., Rajeev Pandey, and Jaswant Singh. Impact of Industrial Wastewater Irrigation on the Soil Characteristics. J of Industrial Pollution Control. 19(1). pp:43-52, 2003.

10. Velu V., Armugam A., Arunachalam G. Impact of Paper Mill Effluent Irrigation on the Yield, Nutrient Content and their uptake in Rice. Madras AgricJounral. 86(1-2). pp:115-121, 1999.

Gravely Soil

0.3

0.3

Clayey Soil

0.3

Silty Soil

Nitrogen Accumulation, mg/l

Nitrogen Accumulation, mg/l

Nitrogen Accumulation, mg/l

Nitrogen Accumulation, mg/l

Nitrogen Accumulation, mg/l

Nitrogen Accumulation, mg/l

0.25 0.25 0.25

0.2 0.2 0.2

0.15 0.15 0.15

0.1 0.1 0.1

0.05 0.05 0.05

0

T1 T2 T3

Treatment Options

Radish Palak Maize

0

T1 T2 T3

Treatment Options

Radish Palak Maize

0

T1 T2 T3

Treatment Options

Radish Palak Maize

fig. 1 : Accumulation of Nitrogen in crops (Cycle III)

Gravely Soil

Phosphorous Accumulation, mg/l

Phosphorous Accumulation, mg/l

25

20

15

10

5

0

T1 T2 T3

Treatment Options

Radish Palak Maize

Clayey Soil

Phosphorous Accumulation, mg/l

Phosphorous Accumulation, mg/l

20

18

16

14

12

10

8

6

4

2

0

T1 T2 T3

Treatment Options

Radish Palak Maize

Silty Soil

Phosphorous Accumulation, mg/l

Phosphorous Accumulation, mg/l

20

18

16

14

12

10

8

6

4

2

0

T1 T2 T3

Treatment Options

Radish Palak Maize

fig. 2 : Accumulation of Phosphorous in crops (Cycle III)

Gravely Soil

Potassium Accumulation, mg/l

Potassium Accumulation, mg/l

35

30

25

20

15

10

5

0

T1 T2 T3

Treatment Options

Radish Palak Maize

Clayey Soil

Potassium Accumulation, mg/l

Potassium Accumulation, mg/l

35

30

25

20

15

10

5

0

T1 T2 T3

Treatment Options

Radish Palak Maize

Silty Soil

Potassium Accumulation, mg/l

Potassium Accumulation, mg/l

35

30

25

20

15

10

5

0

T1 T2 T3

Treatment Options

Radish Palak Maize

fig. 3 : Accumulation of Potassium in crops (Cycle III)

Table-1 : Characteristics of Treatment Combinations

Table-2 : Geotechnical Properties and Classification of Soils