SUPPLY OF NITROGEN

Kaikoura Star, Volume LXVII, Issue 37, 12 May 1947, Page 4

SUPPLY OF NITROGEN

INGENIOUS METHODS USED BY PLANTS. Nitrofying bacteria do not like the acid and airless conditions that prevail in peaty and swampy soils, says the current Ministry of Agriculture news service. Their numbers are, therefore, very low. Also much of the small quantity of nitrate they do produce is washed out of the ground by rain.

Animal life is also sparse on such areas, and there is little natural manure to help supplement the poor supply of nitrogen in such soil.

It would seem that nature has felt sorry for some of the wild plant life that has to live in these soils, for here are found most of the British insectivorous plants; plants fitted with various kinds of mechanism for catching and consuming insects.

Insects Yield Protien.

These plants do not live entirely by the insects they catch, but the lathelp to give the plant a little extra help o give the plant a little extra nitrogen above that of the meagre ration supplied in the soil.

When an insect alights' on a leaf it is held there by some of the hundreds of sticky tentacles. These bend over and press the victims against the leaf-bed and the plant’s digestive juices get to work and break down the nitrogen containing parts of the insect.

Sly Bladderwort.

The Bladderwort, which are in the main water plants, usually found in brakish water, have a most ingenious method of augmenting their nitrogen supply. The leaves of these plants are nearly all under water or are just floating on the surface. On the leaves are small bladder-like sacks, and each sac-k has a one-way valve—it opens inwards but not outwards.

A small water insect, itself in search of food, swims quite unwittingly into the neck of a bladder. As it does so it touches certain hairs. At once the bladder valve opens and the bladder itself expands at a rapid rate, so drawing in water and insect. The valve then closes.* On the inner surface of the bladder are glands capable of secreting digestive juices. At the end of about a quarter of an hour the protiens have been extracted, and the solution containing them has been absorbed by the plant. ThjC bladder is then ready for another insect.

Nature’s way to provide nitrogen for plant life, by z the forn/ation of ni-trogen-noduies on leguminous plants, by the presence of nutrifying bacteria in the soil, and by the means of supplementation above described, illustrate the importance attaching to nitrogen as a form of plant food.