Page 39 - Simply Vegetables Spring 2024

Functions of Lime
(From leaflet 17, Department of Agriculture and Technical Instruction for Ireland, October 1901.)
1. Lime supplies an essential plant food
(Calcium – Ed).
2. It sweetens sour land. Some soils, especially peat (of which there is quite a bit in Eire – Ed) which contain an excessive quantity of acid or sour matter. Lime renders this acid harmless and encourages the growth of more nutritious plants.
3. Lime improves the physical conditions of the soil. It helps to bind light sandy soils together and opens up stiff clays and makes them more easily cultivated. (Lime will bind small particles like clay and some silts and fine sands but the coarser sands do not tend to form crumbs – Ed).
4. It sets free potash. Some soils contain a large quantity of potash, but not in
a state in which it can be of service
to plants. Lime helps to set part of
this potash free from combinations in which it exists in the soil and renders it available for the plant.
5. Lime prevents or at least minimises disease such as finger and toe in turnips (clubroot in Brassicas – Ed). For this purpose, it ought to be applied in the year previous to that in which turnips are grown. Where a field is badly infested with this disease the rotten turnips should be left on the ground and the field should get a good dressing with lime (the turnips would be better fed to cattle and sheep or removed as they would be a source of infection even with the application of lime – Ed)
6. Limefavoursthedecompositionof organic nitrogen and assists in the process of nitrification or in other words it assists to make nitrate in the soil. As already explained, we have three distinct forms of nitrogen – viz, nitrate, ammonia, and organic nitrogen and that only the former is available as plant food. The other two have first to be converted
into nitrate. This is brought about by the agency of germs or bacteria (they are bacteria not germs! – Ed). Before these bacteria can perform their work, they must have fresh air, moisture, a suitable temperature and lime. We can now understand why it is desirable to have lime in the soil and why it is we often see such marked effects after
its application. When we apply lime to soils containing old dung and the roots and refuse of former vegetation, we are simply starting a manufacture for the production of this costly ingredient nitrate (even more costly now owing to the war in Ukraine! – Ed). Some soils
contain as much nitrogen per acre as 100 tons of nitrate of soda and yet if we apply 1 cwt of nitrate, we see results in a few days. What is the reason for this
if we have so much nitrogen present already? The reason is that the nitrogen being in the organic state is of no service to the crop.
Nitrification in the soil is at a standstill,
very likely owing to a want of lime. We may notice in this connection that sulphate of ammonia has to undergo the same change, so that where sulphate of ammonia is applied, sufficient lime must be present if we are to derive full benefit. We have so
far looked at one side of the question and noticed the benefits to be derived from
the judicious application of lime. Let us now turn to the other and see the effects
of applying lime without giving sufficient manure along with it. If we were asked the question, does lime improve or exhaust
the soil, we would be very apt to answer
in the affirmative but on due consideration the answer should be, that unless the
land contains an almost inexhaustible supply of material for the lime to work
upon, or unless plenty of manure is applied along with the lime it may not effect an improvement? Nitrate of soda has been said to act as a “whip,” or a scourge on the land. The same may be said about lime when injudiciously used. If you apply the whip to your horse, you must give plenty of oats along with it. The whip alone will not bring him to his journey’s end neither will lime alone produce a good crop and keep the land in condition. It may stimulate it
for a year or two, but the final result will be poorer crops, and an exhausted soil. This may sound like false doctrine, but it is no new theory; our forefathers were perfectly well aware of this fact, as is evidenced by some of the old sayings which they have handed down to us, such as “Lime makes a rich father, but a poor son,” and also “Lime and marl without manure will make both farm and farmer poor.”
Do not apply lime and manure together as they react, and you lose a lot of the nitrogen from the manure. It is interesting to see what they were writing a century ago and in some ways we have not moved on a great deal although in other ways we have. – Ed
Simply Vegetables 39
Growing Broad Beans with Potatoes
The old system of growing broad beans among potatoes is worthy of consideration at the present time. During the past season there have been numerous cases of successful crops with this association.
1. 2. 3.
The important points to observe are as follows:
The variety of potato should be a first early or at least an early or second early and not a variety producing rank haulm.
The broad bean should be placed between the potato sets at the time the potatoes are planted.
The tops should be pinched out of
the beans as soon as
pods are set at
five nodes.
When the beans are planted in the same
row as the potatoes they may be put in every row, and in the case
of early potatoes closely planted – two beans between each plant.
This season Mr.
Gardiner of Croydon
grew a good crop of beans amongst early potatoes, the latter producing a crop of about 16 tons per acre.
As members will know I am keen
to make maximum use of space to get
maximum productivity but have not heard
of this method before, do any members use it? – Ed.