PLANT NUTRITION

You all knows that all plants require a number of "FOODS' to be able to grow, some of these being obtained from the atmosphere and others from the soil. Carbon is obtained from carbon dioxide in the air and water is absorbed through the roots. The carbon, hydrogen, and oxygen are combined in a series of complex processes known as "Photosynthesis" in the plant to produce the carbohydrates which form the necessary basic building materials for plants tissue. The carbohydrates, in turns, are converted into more complexes substances such as nitrogen, phosphorus and sulphur which are taken up by the roots. This article I would share knowledge with all of you about the plant nutrition based on my study in university and recently read an old book titled ' Know and Grow Vegetables' by P.J. Salter, J.K.A. Bleasdale and Others published by Oxford University Press in 1979 (An old book).

When I teach experienced farmers in the classroom or on the field on the subject of plants feeding can often become heated because they hold strong views on the subjects. This is because they have their own views based on accumulation of experience over the years on feeding the plants. They always talk about Cost, Effectiveness and Countability when choosing the plant feeding material. When I talk to Tan Soo Tiok as a Commercial Leafy vegetable Growers in Sengkang, Bukit Gambir, Johor also as a chairman of Malaysia Vegetables Growers Association, he said the most important to feed his vegetable is to get a cheap source, effective and adequate supply throughout the year. He has a agriculture company selling all chemical for wholesale and retail market in his area. The uncertain price of fertilizer and chemical affects the vegetable productivity and profitability.

Back to plant nutrition, SUNLIGHT is very important in growing vegetable and must sufficient all year round. Area selection is important to the farmers to determine so that the area are not waterlogged, well drain, access to roads and some basic utility. From my experience the selection of vegetable area must certain with source of water. Nutrients can be added to the soil through fertilizers, composts or other manure based on availability and costs. The essential nutrients for vegetable to grows has 6 major nutrients and 6 minor nutrients. The MAJOR NUTRIENTS are NITROGEN (N), PHOSPHORUS (P), POTASSIUM (K), CALCIUM (Ca), MAGNESIUM (Mg) and SULPHUR. The minor nutrients are IRON (Fe), MANGANESE (Mn), BORON (B), ZINC ((Zn), COPPER (Cu) and MOLYBDENUM (Mo).

All the elements required for plants for growth occur naturally in the mots soils, being derived from the weathering of minerals or atmosphere in rainwater (Nitrogen), or the decay of plant material. Soil micro-organisms helps to decomposed slowly organic matter or humus or compost and produce the simplest forms of nitrogen and other nutrients which can be absorbed by the roots of plants. At the same time the nutrients are lost from the soils by LEACHING and this being a particularly large source of the loss of nitrogen in coarse or sandy soils. Crops take up the nutrients from the soils in considerable amounts and the natural cycles of the return of decaying plants waste to the soils is broken if the crop is removed for consumption. The vegetable harvested and consumed bring out all the nutrient in the crops. It is therefore to supply and add extra nutrient as manure or fertilizers to make up for this losses and to ensure good growth of succeeding crops.

If the plants have an insufficient supply of a major or minor nutrients, hey invariably shows visual symptoms of the deficiency. From my observation the farmers must learn and has a maximum skill to identify the symptom either it was due to the nutrient deficiency or due to the attack of pests and diseases. Some of the symptoms are very easy ti indicate but the majority of the symptoms are complicated and need lab analysis. The ability for the farmers to diagnose depend on the experience, soil type, extension service and lab facilities in the vegetable area. Below are some symptoms and treatments of the nutrients deficiency for vegetable growers from my observation and facts from the books.

1. NITROGEN
Lack of Nitrogen (N) usually the first symptoms are pale yellow leaves at the base of the plants where leaves also die prematurely. These leaves have reddish and orange tints in the case of brassicas. The overall growth is poor. The treatment is to apply a top-dressing of nitrogen fertilizer around the plants and water in.

2. PHOSPHORUS
Lack of Phosphorus (P) in some plants no symptoms appear but the vegetable growth are poor ad slow (eg Lettuce). Lower leaves can exhibits a dull and blue green coloration. The treatment is or to cure this problem is difficult with the current crops as phosphate fertilizer cannot be watered in. Try placing some superphosphate under the surface of the soil close to the roots.

3. POTASSIUM
For Potassium (or also known as Kalium) the symptoms shows with the older leaves develop chlorosis (Loss of green colour) followed by scorch around the leaf margins. Brown spots can occur on the leaves. The treatment is to apply Muriate of Potash (MOP) around the plants and water thoroughly.

4. MAGNESIUM

If the plants lack of magnesium it begins on the older leaves; chlorosis between the veins gives a mottled or 'marbled' effect. The veins remain green and leaves fall from the plants. In Tomatoes 'green back' occurs on the fruit ( a green shoulder surrounding the calyx). Apply Epsom salts (known as magnesium sulphate) as a foliar sprays ( 3 oz. for a gallon of water --- You can try to convert in metric unit ?) every two weeks. It may be applied to the soils.

5. CALCIUM

Lack of calcium cause young leaves 'cup' or curls in-wards and the growing points is often deformed or blackened. Calcium deficiency causes 'tip-burn' in lettuces, 'blackheart' in celery and 'blossom end rot' in tomatoes. To overcome this problems we has to spray fortnightly with a calcium nitrate solution (0.5 oz per gallon of water or 3 gram per liter).

Plant nutrition especially on vegetables is an important agronomic practices for vegetable growers to understand. There are many types of fertilizers, compost, foliar and other method to enrich the soil so that the vegetable production harvested according to the production calendar. Correct timing and amounts of fertilizer application are important factors. Follow the perfect timing and ensure the root able to absorb as maximum for a better plant growth.

By,

M Anem
Agonomist
Johor