AS preparations for the 2016/17 season gather momentum, agronomists in Manicaland are conscientising farmers on the need to first conduct soil tests to establish the nutrient content and pH of their soils so that they are informed on fertiliser requirements of specific fields.
Manicaland provincial Agritex officer, Mr Godfrey Mamhare, on Wednesday, said very few farmers were conducting soil tests — a feat that has negatively contributed to the steadily declining yields yearly.
Mr Mamhare said farm soils in Manicaland are tired, overworked and depleted by synthetic chemicals and this winter break was the precise period for one to collect soil samples for testing to establish the nutrient content and pH of their soils.
He said soil testing was a valuable tool in detecting nutrient deficiencies in soils and simultaneously determines the amount of lime required to correct the pH as well as the fertilisers required for sustainable crop production.
Mr Mamhare revealed that different crops have varying pH and dissuaded farmers from randomly applying fertilisers.
“We encourage farmers to use this preparatory window to collect soil samples for testing. Most know about it, but very few comply, with the majority citing the cost component as a challenge,” he said.
In Manicaland soil tests can be done at Africa University at a cost ranging from $20 to $25.
Farmers can have soil tests done either at Windmill and Omnia in Harare for $20 or Zimbabwe Fertiliser Company for free.
“The advantages of having one’s soil tested outweighs the cost component. It is actually an advantage because the farmer’s expenditure will be informed by what has been prescribed through the soil test unlike a situation where one does things blindly,” said Mr Mamhare.
Mr Mamhare warned farmers on the need to apply fertilisers responsibly to attain the best yields.
“Crops have different pH, for maize, the correct pH has to be 5.5 to 6.5 and it is imprudent for a farmer to apply any fertiliser without prior knowledge of what the soil requires. A farmer needs to establish what is missing in a specific piece of land before remedial fertiliser application.
Different soil types have alternative fertiliser requirements and if one over-applies wrong nutrients, it results in imbalances in the soil and has harmful effects on the environment.
“It is best for the farmer to be informed first because if you apply fertilisers in acidity soils without applying the remedial lime, there is no way crops can tape the nutrients,” said Mr Mamhare.
What is soil pH
A soil’s pH is the measure of its alkalinity or acidity based on a scale from 0 to 14. Zero represents harsh acidity, fourteen is extreme alkalinity, while seven is neutral.
Most healthy soils range between a pH of 5,5 and 7,5, and this is the level at which most nutrients in the soil are taken up by plants.
If the soil pH becomes imbalanced, it directly affects the availability of nutrients in the soil.
Lime is applied to soils that are acidic or sour, while soils that are alkaline or sweet can be remedied through the application of sulphate products.
Soil testing can be done once in two years and adjusting the pH of your soil may take several years.
It remains crucial for proper nutrient uptake and plant health.
Manicaland can be divided into dry and moist regions and soils in most areas that fall under the former are alkaline, while those in the moist areas tend to be acidic.
The period spanning June to August is the most ideal time for farmers to take their soil samples for laboratory tests to know the pH levels, including the nutrients needed, before buying any fertiliser for use in their farms.
A soil test costs between $20 to $25 and this can save farmers a lot of money used to buy chemical fertilisers, which their soils may not require in the first place.
Taking a soil sample
Mark different parts of your field using sticks; ensure every part of your farm has been marked.
Dig a hole in each part of the farm that you have marked and take a sample in both the topsoil and the subsoil (top at 20cm depth and subsoil at 50cm depth)
Mix the soil samples collected, break crumbs to make sure the soil is fine in texture.
Dry the soil on a clean plastic sheet.
Put about 1kg of the soil sample into a clean plastic bag.
Label the soil sample clearly with your name and address. If you have taken soil from different blocks of land on your farm, this should be clearly shown in the label.
Indicate the type of crop you intend to grow to get advice on what nutrients are needed for the crop.