Managing soil fertility with white clover
As white clover fills voids in grass stands, forage yields are often increased, particularly when tall fescue and orchard grass stands have thinned. In addition, the clover being the cold season forage can improve the forage distribution and production of summer pastures like Bermuda grass on wetter soils. White clover generally grows late in the winter to late spring and from mid-fall to mid-winter.
The fodder has several soil nutrient requirements for satisfactory establishment and growth. Soil acidity influences the availability of several nutrients and decreases the survival of Rhizobium bacteria, which are necessary for nitrogen fixation. The soil should be limed to a minimum pH of 6. Clovers are highly responsive to potassium and phosphate, so adequate amounts of these nutrients are critical for establishment, persistence and productivity. Below optimal levels of soil P and K are responsible for many clover failures in pastures. White clover performs well on wet soils and persists far better on these soils than red clover. This clover will also perform well on lighter soils, but avoid deep sands.
Because of the high quality of white clover, it is well suited for use as complimentary forage in cold season perennials like tall fescue and orchard grass.
The high total digestible nutrient (TDN) and crude protein content of white clover can increase animal performance on pasture simply due to increased nutrient density. In addition, the higher level of magnesium in clovers decreases the potential risk of grass tetany in the spring. White clover interceded into toxic tall fescue pastures can reduce intake of these toxins. Animals selectively grase the clover, thereby reducing consumption of the toxic grass. This, in combination with the improved diet quality of the clover, greatly improves performance of animals grasing toxic tall fescue.
White clovers are frequently classified in one of three morphological groups: small, intermediate and large. Small types seldom exceed three inches in height and are found in closely grased areas or lawns. These clovers have low productivity and contribute little to grasing animals. Large or ladino white clovers are larger leafed, later blooming and more upright growing than either small or intermediate white clover types.
Under optimal fertility and management, ladino white clovers are more productive than other white clover types. However, ladino clovers are not dependable re-seeders and have fewer stolons and leaves close to ground level.
Because of these reasons, ladino clovers have lower grasing persistence. Intermediate clovers are exactly as their name implies: intermediate. Flowering period and leaf size fall between small and large-type white clovers. Intermediate types typically reseed more dependably than ladinos, possess many stolons and leaves at ground level, and produce more forage than small types. Because of these traits, intermediate types of white clover persist well in grasing situations.
The crude protein content in grass dry matter on the acid soil poor in humus depending on the species and year ranged from six per cent to 14.2 per cent (mean 11.3 per cent) and with lime it increased on average by 0.8 per cent. The effect of white clover on the grass crude protein content in mixed sowings varied with the species and increased by 3.8 to 5.3 per cent on the acid soil, and by 3.6 to 5.9 per cent on the limed soil as most of the Pakistan’s mountainous regions.
Under climatic conditions favourable for plant growth, e.g. in Azad Kashmir, depending on the mean temperature and rainfall, white clover fixes 224 to 600 kg N ha-1. Therefore, it is evident that much attention should be addressed for the establishment and management of white clover on the mountainous regions of country.