You've made your bed, now lie in it
You made a decision and now must accept its consequences– this old idiomis normally used in response to peoplewho are complaining about problems theyhave brought on themselves.
Don’t let yourself fall into the trap of taking the preparation of your seedbed for your new maize crop too casually. It can make or break your crop before it has even started growing and you may be the one moaning about a problem which was actually your own fault!
It is true that many things are going to impact the final yield of any crop in any given season. In a previous article the importance of planter maintenance and planter calibration was discussed and highlighted the importance of accurate seed placement and an ideal plant population but…IF THAT SEED is not placed into a well prepared seedbed, it can also nullify all the good work put into the actual planting operation!
Sometimes we are blessed, as many regions have been this year, with good early rains which give us plenty of time to prepare the soil for planting. But along with this also comes the challenge of early weeds and grasses which have to be controlled because you don’t want to waste all the precious moisture on weeds.
A good seedbed starts already with your primary preparation, whether you are practising traditional cultivation practices like ploughing, conservation or minimum tillage by using tined implements, or even no-till. You always need a good, even seedbed in which to place your seed.
The timing of your seedbed preparation is also important as the results will not be ideal if your soil is either too wet or too dry. This can be determined by a simple hand test in which you take a handful of soil and squeeze it. Does it feel sticky? Can you form a ball that sticks together? Does it form a ribbon when pressed between your thumb and forefinger? If this is true then there is too much moisture to start your seed bed preparation.
Soils ready for seed bed preparation should crumble easily between your fingers. You don’t want to do your final preparation when the soil is either too wet or too dry! On the one hand you will have a too fine seedbed which can easily compact the surface and tend to blow away when the winds come (wind erosion) or if it is too dry you may have big clods which won’t break down and will affect the seed-soil contact causing poor and uneven germination. When the seed bed is just right, i.e. not too fine and not too rough, then the levelness or evenness is the next important aspect.
When your seedbed is as it should be, it allows the seed to be placed at an even depth and plants are more likely to germinate simultaneously to present an even stand. The depth of planting is also likely to be more uniform which encourages the seed to emerge simultaneously and grow at the same pace. This helps the seeds to compete equally for the water and nutrient available in the soil and will ultimately return a better yield.
The seedbed preparation process achieves many things like:
- Killing weeds before planting;
- Incorporating crop residue, manure, nutrients and herbicides into the soil;
- Reducing soil compaction;
- Manipulating the soil surface to minimise soil erosion;
- Enabling the planter to provide consistent seed depth and spacing;
- Conserving soil moisture;
- Enabling soil moisture below the seed to move up to the seed as the soil surface loses moisture;
- Minimising soil clods at the seed depth for maximum soil-seed contact while providing some clods on the surface to minimise soil erosion; and
- Reducing soil crusting which prevent the seeds from emerging evenly.
Always remember that although the maize seed itself looks quite big and robust, it is the tender new roots which need to develop in the seedbed and they have difficulty growing in compacted soils. If the roots are unable to penetrate the soil then their moisture and nutrient uptake will be reduced limiting yield potential already at this early stage.
Seedbeds must be prepared then with the aim of achieving quick, even germination and unhindered early growth. Furthermore this should be done as close to planting time as possible but if there is a rainfall between seedbed preparation and planting, be patient and wait for the soils to dry out enough before planting.
Article submitted by Jenny Mathews, Pula Imvula contributo.r
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Publication: November 2015