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Study on soil and nutrients loss with soil textures and two crops during rainfall

Seung-Oh Hur, Won-Tae Kim, Kang-Ho Jung and Sang-Keon Ha

RDA, National Institute of Agricultural Science & Technology Soil Management, Suwon, 441-707, Korea,
www.rda.go.kr

Email sohur@rda.go.kr , wontae66@rda.go.kr , stealea@rda.go.kr , ha0sk@rda.go.kr

Abstract

This study was carried out to assess the effect of soil texture and crops on soil erosion and nutrient loss during rainfall. Although rainfall was frequently received for four month from April to September, yet soil erosion occurred only on bare soil, with runoff rate of about 36.9%. This was because selection of crops with high ground cover prevented the occurrence of bare soil surface. Nutrients loss from bare soil was two times bigger than soil covered with crops, resulting in higher nutrient contamination of rivers or streams. The total nutrients loss of peanut on loam (L) and clay loam (CL) soil was similar with that of maize except for sandy loam (SL) soil with peanut. Therefore, cultivating peanut on SL soil will be in a better position than cultivating maize in the side of nutrients conservation and pollution decrease in river. But, the aspect of nutrients loss in L or CL soil showed similar trends. Consequently, crop cultivation having high ground cover during rainfall can be great agricultural practices resulting in decreasing runoff, soil and nutrient loss.

Key Words

Soil erosion, Water balance, Soil texture, Crop management

Introduction

The topography of the land in Korea consists of approximately 65% mountainous terrain. Uplands are distributed widely in valleys, alluvial fans, mountain foot slopes, hills, and mountainous areas, and are mainly located in areas with a slope above 2 %, which can result in accelerated soil erosion. In Korea, average rainfall for 30 years (1971-2000) is 1,310mm, which mostly occur in summer so that there is a potential for soil erosion and nutrient loss on upland on hillslope in the early rainy season because of incomplete coverage of the soil surface. Damages by soil loss lead to a decrease of productivity by arable land loss (Jung et al. 1998, Lee et al. 1998) and burying of waterways or reservoirs by sedimentation of lost soil (Oh et al. 1995, Kim et al. 2003) and river pollution induced by nutrients loss (Kim et al. 1997, Jung et al. 1998, Jung et al. 2000). An appropriate crop management to reduce soil and nutrients loss is a main key for land conservation and non-point pollution management so that agricultural practice methods for soil erosion control have to be developed. But, the control of soil erosion is not easy because it appears differently with rainfall intensity, cultivation period and season of crop, ground coverage, surface roughness and soil water content. Therefore, this study was carried out to assess the effect of soil texture and crop on soil erosion and nutrient loss from arable land using lysimeter during rainfall.

Methods

This study was carried out in NIAST (National Institute of Agricultural Science & Technology) in Suwon, located in middle part of Korea. The site has lysimeters constructed with L, SL, CL soils, with 15% gradient, 5m length, 2m width and 1m depth. Crops grown were maize and peanut with three replicates and bare soil is used as control treatment. The runoff and sedimentation tank for measurement of runoff, percolation, soil and nutrient loss was made, and rainfall gauge (Model 260-2501, NovaLynx Corp., USA) was set up for measurement of precipitation. FDR sensors (Model EnviroSCAN, Sentek Sensor Tech., Australia) were installed for soil water content and the other weather data were obtained from weather station. 500 mL of outflow water from sedimentation tank was and filtered for analysis. Nitrate was determined by distillation method, phosphorous by Lancaster method, and cations by ICP (GBC Integra XMP, Australia). Soil loss was measured by dry soil weighting method after 500mL~1L of outflow water filtered. Soil characteristics of experimental field are shown in Table 1. Fertiliser applications for maize were (N-P-K) 343-285-313 ㎏ ha-1, for peanut were 280-193-258 ㎏ ha-1, . An component quantity(N-P-K) of compost for bare soil were 170-20-148 ㎏ ha-1 .

Table 1. Characteristics of experimental field

Soil texture

pH
(1:5)

OM
(g/kg)

Av. P2O5
(mg/kg)

Ext. Cations (cmol+/kg)

K

Ca

Mg

SL

6.1

8

63

0.29

2.4

0.8

L

6.5

4

22

0.19

3.5

1.1

CL

6.1

14

388

0.92

5.7

1.7

Results

The annual rainfall during experiment period was 1146.9mm, and 76% (874.4mm) of the rainfall was received from July to September. Annual erosion indices (EI30) expressing soil erosion factor showed also values focused on July to September as 263(83%). Erosion index in Table 2 used data above 12.7mm per one rainfall event in this study. If there was no rainfall event longer than 6 hours, the precipitation was calculated as one rainfall event. Soil erosion factors were estimated from Nomograph developed by Wischmeir (1981).

Table 2. Erosion index by monthly and annual rainfall characteristics

Classification

April

May

June

July

Aug.

Sept.

Total

Rainfall
(mm)

52.5

77.0

143.0

323.6

280.3

270.5

1,146.9

Erosion index
(EI30)

7.8

15.2

31.3

86.4

115.8

60.8

317.3

Effect of soil texture on runoff, drainage, water balance and soil loss by rainfall are shown in Table 3.. Total precipitation to occurrence period of runoff was 956.3mm. In the case of quantity of outflow water, bare soil was 30% more than cultivation area on all soil texture so that soil loss from crop cultivation area existed hardly but soil loss depths of bare soil were 1.37mm on SL, 3.73mm on L and 4.97mm on L soil. This implies that crop cultivation has an advantage in reducing runoff and soil loss.

Table 3. Effect of soil texture on runoff, drainage, water balance and soil loss
(Unit: ton ha-1)

Classification

Sandy loam

Loam

Clay loam

Bare

Maize

Peanut

Bare

Maize

Peanut

Bare

Maize

Peanut

Runoff (%)

3,355
(35.1)

310
(3.2)

160
(1.7)

3,490
(36.5)

340
(3.6)

290
(3.0)

3,725
(39.0)

400
(4.2)

310
(3.2)

Drainage (%)

2,219
(23.2)

1,225
(12.8)

860
(9.0)

2,160
(22.6)

1,835
(19.2)

2,035
(21.3)

1,840
(19.2)

1,805
(18.9)

1,805
(18.9)

ET (%)

715
(7.5)

830
(8.7)

771
(8.1)

715
(7.5)

830
(8.7)

771
(8.1)

715
(7.5)

830
(8.7)

771
(8.1)

CSW (%)

2,657
(27.7)

3,676
(38.5)

3,011
(31.4)

2,897
(30.3)

4,325
(45.2)

3,430
(35.9)

3,013
(31.5)

4,689
(49.0)

3,985
(41.7)

RE (%)

617
(6.5)

3,522
(36.8)

4,761
(49.8)

301
(3.1)

2,233
(23.3)

3,037
(31.7)

270
(2.8)

1,839
(19.2)

2,692
(28.1)

Soil loss

13.7

tr

tr

37.3

tr

tr

49.7

tr

tr

ET : Evapotranspiration CSW: Change of soil water content RE : Rainfall excess(including interception)

Nutrients loss by soil texture and crops are shown in Table 4. Nutrients loss from bare soil were entirely heavier than cultivation area. When maize was compared with peanut, nutrients loss of upland with maize were more than those of peanut on SL and CL soil, but those of peanut cultivation area was bigger than maize on L soil. SL was more than CL and L in the case of nutrients loss on maize cultivation area. Nutrients loss of L was more than those of CL and SL on peanut cultivation area. The order of nutrient loss on bare soil was CL>L>SL.

Table 4. Aspect of soil loss by each soil texture and crop

Nutrients
kg/ha

Crops

Runoff

Eroded soil

Drainage

Total

SL

L

CL

SL

L

CL

SL

L

CL

SL

L

CL

N

Maize

1.2

1.4

1.6

tr

tr

tr

11.9

10.5

10.5

13.1

11.9

12.1

Peanut

0.6

1.2

1.2

tr

tr

tr

7.6

11.2

10.3

8.2

12.4

11.5

Bare

13.5

14.1

15

0.2

0.2

0.6

4.8

11.6

10.6

18.5

25.9

26.2

P

Maize

0.9

1

1.2

tr

tr

tr

0.8

0.6

0.6

1.7

1.6

1.8

Peanut

0.5

0.8

0.9

tr

tr

tr

0.6

0.6

0.4

1.1

1.4

1.3

Bare

2.4

3

3.2

1.8

2.4

3

0.6

0.5

0.4

4.8

5.9

6.6

K

Maize

1.4

1.6

1.8

tr

tr

tr

13.6

12.1

12

15

13.7

13.8

Peanut

0.7

1.3

1.4

tr

tr

tr

8.7

12.9

11.9

9.4

14.2

13.3

Bare

15.5

16.1

17.2

3.5

5

5.3

5.5

13.3

12.2

24.5

34.4

34.7

Conclusion

Crop cultivation reduced runoff during rainfall and the runoff decrease on SL soilwith peanut cultivation was far superior than on other soil texture and crop. Crop with great ground coverage had an advantage for decrease of soil loss and runoff. The quantity of drainage water of CL bare soil was similar to cultivation area on CL soil because electronic characteristics of clay and soil pore filled by very small size particles suppress drainage of rainfall. Nutrients loss on bare soil during high rainfall was two times bigger than soil with crops cultivation so that there was a high potential for nutrient contamination of rivers or streams. Therefore, agricultural practices avoiding bare soil situation during rainfall is recommended for arable land. The total nutrients loss from soil growing peanut on L and CL soil was similar to that of maize except for SL soil with peanut. Therefore, cultivating peanut on SL soil will result in lower nutrient loss than cultivating maize, thus reducing nutrient pollution of rivers or streams. However, nutrients loss from L or CL soil showed similar trends. Consequently, crop cultivation having high ground cover during rainfall is a recommended agricultural practice to reduce runoff, soil and nutrient loss.

References

Kim SM, Park SW, Kang MS(2003). Estimation of sediment yield to Asan bay using the USLE and GIS. Journal of Korea water resources association Vol.36 (6) pp. 1059-1068

Kim JT, Park SW(1997). Development and application of a GIS interface for the agricultural nonpoint source pollution (AGNPS) model (III) - Model applications -. Journal of the Korean society of agricultural engineers Vol.39 (3) pp. 138-143

Oh SJ, Jung PK(1995). Effect of soil erosion control with different grass species on slope land. RDA journal of agricultural science Vol.37 (2) pp. 246-250

Lee NJ, Oh SJ, Jung PK(1998). Soil loss and water runoff in a watershed in Yeoju. Journal of Korean society of soil science and fertilizer Vol.31 (3) pp. 211-215

Jung YS, Yang JY, Park CS, Kwon YK, Joo YK (1998). Changes of stream water quality and loads of N and P from the agricultural watershed of the Yulmunchon tributary of the Buk-Han River Basin. Journal of Korean society of soil science and fertilizer Vol.31 (2) pp. 170-176

Jung JB, Kim MK, Kim BJ (2000). Surface runoff loss of nitrogen and phosphorus from peach orchard. Journal of the Korean agricultural chemistry and biotechnology Vol.43 (2) pp. 124-129

Jung PK, Oh SJ, Lee NJ(1997). Soil conservation management on slope land: study on soil and nutrients loss on slope land. RDA NIAST Annual research report Agricultural environment department pp. 269-271

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