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FACTSHEET


No. 9: 20 YEAR RECORD OF DRAINAGE BENEFIT

by Ross W. Irwin

Background
Crop data comparing the yield from matched tile drained and undrained fields are scarce in the literature. Most comparison data were derived from small research plots. These data may not be transferrable to reflect field scale production. The benefits of tile drainage has always been of interest. In 1970, a Fact Sheet on Drainage Benefit was prepared based on a search of existing literature. In 1974, personal interviews with 100 farmers across Ontario solicited opinions on drainage benefit. The interviews reported that tile drainage effected satisfactory increases in crop yield. In the "Survey of Crop Yields", December 1976, collected by the Farm Economics Branch, O.M.A.F. a question was asked about the effects of tile drainage on crop yield.. All of the above information were analysed and reported in a revised Fact Sheet on Drainage Benefit. In 1979, the Crop Insurance Commission of Ontario permitted the addition of questions regarding the presence of tile drainage in their insured field samples. A computer program was developed to analyse the large data base. These data presented here are courtesy of the Commission, now AGRICORP.

These data permit a comparison of actual farm crop yield from tile drained and untiled land on a provincial basis. The same data base would permit an analysis of drainage benefit by crop on a county basis; however, the sample numbers become smaller and comparisons have greater variation.

These data should also apply to northern states of the U.S. which are climatologically similar to Ontario; that is, where the 25 percent chance of a killing frost is May 15 to October 10 and the normal growing degree days will be greater than 2,800.

The Data Base
The Crop Insurance Commission of Ontario was established in 1966 to provide a three-way crop insurance program. Participants were the Provincial and Federal governments and the farmer. The mechanism of the program will not be discussed here but basically a bench-mark yield was established for each farmer for each crop. Crop insurance was paid based on a deviation from this bench-mark yield.

Local crop insurance salesmen and/or adjusters completed a form recording the following information for each insured field: Name, Address, Lot and Concession, Township, County, Year, Crop, Contract Number, Acres Insured and Total Harvested Yield. The first three entries which could identify a specific farm were privileged and were not available for this analysis. For 1979, and subsequent years, a question was asked regarding the presence of tile drainage in the insured field. There was some uncertainty regarding whether land was owned or rented but this was clarified in the 1982 report.

After 1999 the field data were no longer recorded and evaluated by an independent insurance adjuster but by each insured land owner. This decision may create some uncertainty in the data so after 20 years the project has been terminated. Twenty years is a very lengthy data base upon which accurate comparisons may be made.

Drainage Data
A review of the completed forms indicated the following options for analysing comparisons of crop benefit from tile drainage.

A] All insured acreage was tile drained.

B] Part if the insured acreage was tile drained.

C] None of the insured acreage was tile drained.

D] No answer to the question, interpreted here to mean no tile drainage.

There is a caution. The definition of "tile drained" regarding any insured field is that reported to the adjuster by the farmer. That is, the farmer has stated the insured land has tile drains installed. Another farmer may report that tile drainage has been installed but may be inadequate for a similar situation. The data are conservative from this aspect of the questions.

Each of the above options have been analysed. However, only comparisons A and C are reported here. The data have also been analysed by comparing options A + B against C + D. The number of fields analysed increases but the results of the drainage data changes little.

Insured crops for which the drainage question were recorded are: Winter Wheat, Red Spring Wheat, Spring Grain; Grain Corn; Soybeans, White Beans, Coloured Beans, Canola, and Sunflowers. Annual crop prices were derived from those shown in the annual issue of OMAF Pub. 20, "Agricultural Statistics for Ontario". Prices for the last four crops are not included in that publication and is the reason some economic benefits are omitted.

The table below are average values for the province. That is the reason that yields seem low. The sample size is very large and the data is considered to be accurate. Brief comments on each crop follow the table.

Crop

 

Years

# of Records

Yield Tiled
bu/ac
or
lbs/ac*

Yield No Tiled
bu/ac
or
lbs/ac*

Total Acres Tiled

Total Acres No Tile

% Increase in Yield

% Acres Tiled

Corn

20

209,098

115

89

11,189,949

7,420,135

29

60

Soybeans

20

177,853

39

31

10,865,953

5,527,814

26

66

Wheat W

20

136,510

62

45

3,710,608

1,840,279

38

67

Grain, Spr

20

130,566

2,663*

1,934*

2,337,036

2,441,330

38

49

Beans, Wh

20

29,615

1,554*

1,284*

97,326

336,683

21

22

Canola

10

5,170

1,598*

1,420*

147,591

177,458

13

45

Beans, Col

20

5,164

1,438*

1,302*

234,637

82,786

10

74

Wheat, Spr

10

4,552

44

33

125,644

91,417

33

58

Sunflower

10

337

1,409*

1,264*

6,837

3,561

11

66

Data Analysis

Grain Corn - with almost 210,000 fields analysed, the table shows that 60 percent of the crop was grown on tile drained land over the 20 year record. In the period 1979 - 1982, only 48 percent of the corn crop was grown on tiled land. Improvements in crop variety has permitted the crop to be grown outside the traditional Southwestern Ontario base. The insured acreage has increased three times by 1995 - 1998 and the much larger acreage is grown on land that is 63 percent tiled. LICO drainage contractors have made a substantial contribution through the drainage of cultivated farm land for corn in Ontario.

The yield increase for corn grown on tile drained land vs corn grown on untiled land was 29 percent over the 20-year period. Again note the actual 20-year crop yields are the average for the province. Many counties report much higher yields. Grain corn is now grown in almost every county and district in Ontario. Over 20 years the average annual loss from growing grain corn on untiled land was $77.71 per acre.

Soybeans - the second highest insured crop acreage grown in Ontario. The data shows that 66 percent of the crop is grown on tile drained land. The average annual increase in yield for soybeans grown on tile drained land vs soybeans grown on untiled land was 26 percent.

Soybeans are no longer restricted to Southwestern Ontario but have spread across most of the counties of Ontario. Over 20 years the average annual loss for soybeans grown on untiled land was $48.92 per acre.

The insured soybean crop has increased seven times in acreage when comparing the periods 1979 - 1982 and 1995 - 1998. In the earlier period farmers generally planted the crop on tile drained land, only 22 percent remained untiled. In the later period soybeans were grown on 36 percent untiled land. There is room for improvement by more tile drainage for this crop.

Winter Wheat - the third largest insured crop is grown across the province on 67 percent tiled drained land. The increase in yield for winter wheat grown on tile drained land was a remarkable 38 percent. The average annual loss for winter wheat, over 20 years, when grown on untiled land was $62.71 per acre.

Spring Grain - includes oats, barley and mixed grain. These insured feed grains are grown principally in Northern Ontario and in Perth, Huron and Wellington counties. The crops were grown on 49 percent tile drained land and reported an increase in yield of 38 percent. Over 20 years the average annual loss for spring grain grown on untiled land was $20.97 per acre. In the period 1979 - 1983 spring grain was planted on fields which were only 34 percent tile drained. The benefits of tile drainage have been recognized and in the period 1994 - 1998 only 51 percent of the land remained untiled.

The following are minor crops with respect to insured acreage.

White Beans - are principally grown on tile drained land in Huron, Perth and Middlesex counties. About 22 percent of the land used to grow white beans is now tile drained. The long term increase in yield from drainage was 21 percent.

Canola - is a recent crop in Ontario, grown for its oil. The insured crop is principally grown in Wellington, Dufferin and Simcoe counties and in Northern Ontario. Only about 45 percent of the land used to grow this crop is tile drained. The increase in yield when grown on tiled land was only 13 percent.

Coloured Beans - a low acreage insured crop grown on 74 percent tile drained land in the counties of Middlesex, Huron, Perth and Oxford. The increase in yield when grown on tiled land was 10 percent.

Red Spring Wheat - a very small insured acreage grown in Wellington, Perth, Bruce, Simcoe and Dufferin counties. About 58 percent of the insured acreage was tile drained. The increase in yield for Spring Wheat grown on tiled land was 33 percent. The average annual loss for Red Spring Wheat on untiled land was $95.56 per acre.

Sunflower seed is grown on a very small acreage in Essex and Wellington counties. About 66 percent of the insured acreage is tile drained but the increase in yield was only 11 percent.

It pays to tile drain crop land!

 


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