Vegetable Chops - Ash Analyses

Name of Crop.

Potash.

Phosphoric Acid.

Lime.

Sulphuric Acid.

Iron Oxide.

Magnesia.

Soda.

Chlorine.

Silica.

Cabbage

31.95

12.93

15.66

8.61

8.32

4.93

2.51

7.99

4.99

Cauliflower ...

34.39

25.84

3.07

11.16

3.67

2.38

14.79

2.78

1.92

Turnip

5012

16.41

13.02

6.95

0.32

2.00

3.62

6.32

1.21

Kohl.rabi

48.69

16.75

13.65

6.82

0.48

3.18

3.89

5.31

1.23

Radish

23.65

40.12

8.92

6.97

2.10

3.64

3.01

3.59

8.00

Peas ...

20.10

40.10

6.90

2.00

1.40

8.90

17.30

1.20

2.10

Beans

42.50

34.66

6.00

3.50

0.40

7.30

334

1.40

0.90

Carrots

48.20

18.43

13.86

6.30

0.35

3.71

2.68

5.21

1.24

Parsnips

47.10

19.25

14.62

7.21

0.40

363

2.00

4.10

1.66

Celery

22.07

11.58

...

5.58

2.66

5.82

. . .

. . .

3.85

Beetroot

4911

15.26

8.82

7.00

0.22

7.23

4.83

6.18

1.33

Lettuce

46.26

8.21

6.24

5.36

0.21

2.15

6.08

5.49

20.00

Endive

37.62

3.21

12.02

5.92

0.29

213

11.00

2.03

24.78

Rhubarb

30.00

18.13

14.21

5.04

3.68

7.33

9.78

2.03

8.06

Onion

32.35

15.09

13.66

8.34

12.29

2.70

8.04

4.49

3 04

Asparagus ...

6.01

18.51

439

4.13

3.31

3.03

34.21

12.94

13.47

Jerusalem

44.62

14.97

8.36

5.21

4.31

6.89

9.63

2.98

13.03

Artichoke

Potato, tubers

55.75

12.57

2.07

10.62

0.52

5.28

1.86

7.10

4.23

The quantity of these foods to an acre may be seen from the following analysis of Broadbalk Field, Rothamsted. The soil had not been manured for fifty years, and at 9 in. deep the weight of an acre was 2,500,000 lb. containing -

Carbon ...

22,250 lb.

Nitrogen

2,500 „

Soda

1,500 „

Potash ...

6,750 „

Magnesia

9,000 „

Lime

62,250 „

Alumina

112,250 „

Oxide of iron ...

85,000 „

Phosphoric acid

2,750 „

Sulphuric acid ...

1,250 „

Carbonic acid ...

32,500 „

Total ...

338,000 „

This particular soil lost about 420 per cent, or 105,000 lb., on ignition; 1253 per cent, or 313,250 lb., was soluble in hydrochloric acid; and the undissolved siliceous matters were 83'27 per cent, or 2,081,750 lb.

These figures would indicate that there is an inexhaustible supply of food in the soil - far more than could be absorbed by many crops in the course of several years.

It has been estimated that an acre of fruit trees would require each year about 200 lb. lime, 150 lb. potash, 75 lb. nitrates, 50 lb. phosphoric acid. It would thus take over 311 years to exhaust all the lime in the Broadbalk Field at Rothamsted, 45 years to exhaust all the potash, 33 years to exhaust all the nitrogen, and 55 years to exhaust all the phosphoric acid. And it must be remembered that these quantities are given for an acre of ground unmanured for 50 years, and taken from only 9 in. deep.

In an American experiment, soil at 1 ft. deep (not 9 in.) gave 3,225,000 lb. weight to the acre, and was estimated to contain -

Phosphoric acid ... ... 6,772 lb. per acre.

Potash .........32,897 „ ,,

Lime......... ... 47,407 „ „

The Science of the Soil m

An average of the results of forty.nine analyses of typical soils in America showed that the first 8 in. of surface soil contained -

Nitrogen ......... 2,600 lb. per acre.

Phosphoric acid ... ... 4,800 „ „

Potash .........13,400 „ .

In a good Hertfordshire soil analysed by Dr. Voelcker the following quantities of plant foods were found: -

Phosphoric acid

... 4,569 lb. per acre (over 2 tons).

Potash

... 10,483 „

,,

( ,, 5 ,, ).

Lime

... 74,188 „

,,

( ,, 33 ,, ).

Magnesia ...

... 9,676 „

,,

( ,, 4 ,, ).

Sulphuric acid

... 4,569 „

,,

( ,, 2 ,, ).

Nitric acid ...

22 „

,,

Nitrogen ...

... 2,397 „

,,

( ,, 1 ton).

The surface soil from 9 to 12 in. deep is usually regarded as being more fertile than the subsoil beneath. Although farmers may accept this statement, many modern gardeners question it, for experience proves that by turning the soil over to a depth of 2, 3, and even 4 ft. magnificent crops can be secured. Indeed this has been proved for centuries by Chinese and Japanese gardeners, who are adepts at deep cultivation. Of course if the upper 9 or 12 in. of soil only are cultivated and manured it is possible to prove that it is richer in available plant food than the layers of soil immediately beneath. But actual practice proves that if the subsoil is also cultivated and manured, and brought up to be acted upon by the weather, it will gradually yield up the foods it contains.

The following comparison between the plant foods in the soil and subsoil is worth consideration: -

Surface Soil.

Subsoil.

Silica, insoluble ..

59.26 per cent.......

53.71 per cent.

Silica, soluble

2.63 „ ......

3.96 „

Alumina ...

3.12 „ ......

3.27 „

Iron

6.10 „ ......

7.15 „

Lime

5.36 „ ......

8.85 „

Magnesia...

0.02 „ ......

0.21 „

Soda

0.93 „ ......

1.02 „

Potash

1.53 „ ......

1.89 „

Carbonic acid

7.00 „ ......

1036 „

Phosphoric acid ...

0.13 „ ......

0.49 „

Sulphuric acid ...

0.63 „ ......

0.94 „

Chlorine ...

1.20 „ ......

1.32 „

Organic matter ...

12.09 „ ......

6.83 „

100 00 „

100.00 „

With the exception of organic matter (which can be easily supplied by means of stable manure and other vegetable and animal refuse) these figures indicate that the subsoil really contains, on the whole, a larger supply of plant food than the upper crust. Owing to the fact that the latter is usually the only portion cropped it is not unnatural that it should lose some of its available food and thus become poorer. Thus one hears of a soil becoming "exhausted", by which is meant that it no longer yields the same quantity of good saleable produce as formerly, notwithstanding the fact that it has been cultivated and manured. The " top spit", which is therefore usually regarded as the best soil, may be really in a worse and poorer condition than the soil beneath it, owing to constant cropping, and because it is "always carefully kept on top".

If any reliance at all is to be placed on the figures quoted above from Dr. Voelcker and others, it is palpable that there is an enormous supply of plant food locked up in the earth, and if it can only be made available - not all at once, which would be fatal, but gradually - the cultivator has but to work his soil properly to liberate this food.

But this is just where the chemical theorist fails and where the cultivator comes in. Jethro Tull and the author of the Lois Weedon System of Cultivation were misled like many others with figures showing the abundance of food contained in their soils, but in practice they failed to obtain the best results. They practised deep cultivation, but they overlooked the fact that something besides a good supply of mineral food was also necessary. They overlooked the important factor of organic or stable manure and humus generally. It is as true now as in the days of Adam, notwithstanding our advance in the science of agricultural chemistry, that the gardener or the farmer who would reap the best results from his land must not only cultivate deeply, but he must also " load his fallow ground with fattening dung".