Seedbed conditions

Seedbed conditions - the seed rate should be increased in cloddy and stony conditions where seedhng growth may be poor. 

Seedbed conditions (higher rates in very diy, cloddy and stony soils). 

Seedbed conditions and time of sowing, e.g. higher seed rate when sowing late in the autunm or early in the spring. 

As soon as possible after mid-February but seedbed condition and soil temperature are important considerations. 

Field losses may vary from 20% down to 5% depending on sowing time and seedbed conditions. 

In studies of earthworm activity in forest soils of Wisconsin, Nielsen and Hole (1964) estimated that the total live weight of earthworms per acre was 1,980 lb., more than half of which was the imported L. terrestris. They state that this species is changing the process of incorporation of organic matter into the soil with accompanying changes in soil microclimate, erosion, condition of seedbed, rate of nutrient cycling, and depth of A-horizon. ... 

Cultivation of soils that are somewhat below optimum moisture will produce less damage to aggregates but the production of a good seedbed under such conditions requires more intensive tillage. The cultivation of a very dry soil will result in the shattering of some of the clods and the production of many dust particles. The overall effect on aggregate formation in such a soil, apart from the breakup of clods, is negligible. If the main purpose of the cultivation is to break up clods it is advisable to wait until moisture conditions are more favorable. 

The physical condition existing in a loam or clay soil is very dependent on whether past tillage operations were conducted at the proper time - that is, when neither too wet nor too dry. Very sandy soils can be plowed at almost any time but this is not true of the heavier soils they are either too wet or too dry most of the time. If these heavy soils are too dry, tillage is not very effective in making a fine seedbed free of clods. If the soil is too wet, portions of it are puddled, leaving clods when dry. A shiny, slick surface left by the moldboard plow serves as visible evidence that the soil was plowed when too wet. 

Tilth is a term used to describe the condition of the soil in a seedbed. For example, the soil may be in a finely-divided state or it may be rongh and litmpy. Whether a tilth is suitable or not partly depends on the crop to be grown. In general, a small seeded crop requires a finer tilth than large seeds. 

Some cropping systems are much more prone to water erosion than others. The most susceptible land use is when crops are harvested in the auturrm under adverse soil conditions which can happen with forage maize and field vegetables. Long term leys and permanent pasture usually pose little risk. Soils with a good crop cover are much less susceptible than where there are fine seedbeds and or bare ground. 

Most active in moist and humid conditions. An attack can be more serious when the seed is direct-drilled if the slit has not been properly covered or if the seedbed is loose, cloddy and trashy. Populations and damage are highest on heavy textured sods. 

Some pyrethroid are approved for use when damage severe particularly in backward crops when conditions are dry. Damage is worse if there is a cloddy seedbed. 

Rotary power harrows can result in much better movement of the soil in one pass. They are most valuable on the heavier soils when preparing fine seedbeds for potatoes, sugar beet and other crops. Power harrow/drill combinations are used by some farmers as one-pass operations to prepare seedbeds for cereals. They can be used in conditions where ordinary drills may not be appropriate. 

This type of implement consists of curved blades which rotate around a horizontal shaft set at right angles to the direction of travel. The shaft is driven from the power take-off of the tractor depth is controlled by a land wheel or skid. This implement can produce a good tilth in difficult conditions and, in many cases, it can replace all other implements in seedbed preparation. A light fluffy tilth is sometimes produced which may cap easily if wet weather follows. The fineness of tilth can be controlled by the forward speed of the tractor for example, a fast speed can produce a coarse tilth. It is a very useful implement for mixing crop remains into the soil. The rotating action of the blades helps to drive the implement forward and so extra care must be taken when going down steep slopes. 

Accurate spacing and uniform depth of planting of seed in well-prepared seedbeds are very important if optimum yields are to be obtained. This usually involves doing seed counts/kg and carefully setting the drill. Narrow (10-12 cm) rows are preferable. Broadcasting seed can be successful provided the seed is distributed uniformly and properly covered. Stony soils, wet and cloddy conditions can give crops a poor start. 

Fire is essential to the maintenance of western larch in natural populations. High-intensity fires thin stands, reduce fuels, and prepare seedbeds that promote establishment of shade-intolerant conifers, particularly the western larch. Without fire, shade-tolerant associates eventually replace the larch (Schmidt and Shearer, 1990). Even-aged silvicultural systems best fit the ecological requirements of western larch. These systems provide an adequate seed source and the microsite conditions needed for establishment. Site preparation of prescribed burning or scarification to reduce the duff layers and vegetative competition is often necessary for its successful regeneration (Bums, 1983). 

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