Crop rotation as soil administration device



By George Katongole

Crucial position of crop rotation is to stop the build-up of pest and illness issues within the soil to which a crop is inclined.
If the identical crop or an identical kind belonging to the identical household is grown in the identical subject, it can endure from the amassed pests and ailments from the earlier crop and will not develop properly.

One technique to keep away from this problem is fallowing, or planting tolerant or resistant crop to the actual pest or illness.
Higher nonetheless, a crop from a special household will be planted. However specialists advise that there’s extra to rotation than switching crops.

In accordance with Henry Ssali, a soil fertility administration researcher at Nationwide Agricultural Analysis Laboratories (NARL-Kawanda), an built-in strategy that includes use of natural and inorganic fertilisers, organic nitrogen fixation, rotations, agroforestry, in addition to correct soil and water practices, are necessary in lowering soil degradation.

In a examine revealed in 2000 within the Uganda Journal of Agricultural Sciences, Ssali explains that within the early phases, Uganda’s soils have been thought-about fertile and little was completed to enhance productiveness. However after finding out the causes of infertile patches within the nation like ‘lunyu’ soils in central Uganda and sterile acidic swamps, a scientific strategy was adopted.

“Nevertheless, it was quickly realised that crop yields declined beneath steady cultivation resulting in the really useful use of natural supplies, crop rotations, and grass rests, amongst others to enhance and maintain soil productiveness,” says Ssali.
James Mugerwa Sebudde, an extension employee in Buvuma District, says sure ideas have to be adopted for efficient crop rotation. Mugerwa says rigorously chosen rotations can significantly help management of plant ailments and nematodes.

“Generally a one-year break is enough for illness management, whereas for different ailments quite a few years of rising a non-host crop is required to sufficiently scale back inoculation,” he says.


Some ailments enter the sector on contaminated seed, whereas others equivalent to wheat leaf rust and mildew, are airborne. “This exhibits that different methods, apart from rotations, are wanted to cope with such ailments,” he says.
Throughout crop rotation, consideration needs to be made in what situation a specific crop will depart the soil for the succeeding crop.

In accordance with Mugerwa, ailments forestall the identical issues. “By precept, many farmers observe leaf crops after root crops. However one can find yourself attaining nothing,” he says.

In case of a root crop equivalent to carrots and spinach (a leaf crop), each are susceptible to root knot eelworm.
“So rotating between them won’t do away with the nematodes,” he says.

He provides {that a} farm contaminated with beet cyst eelworm which stunts progress, inflicting wilting and yellowing and in some cases dying of crops, can’t be adopted with crops from the brassica household equivalent to cabbage, beetroot, sugar beets, broccoli, and radish as a result of the build-up of the pest will proceed.

For a similar cause, it’s a mistake to observe tomatoes with a crop inclined to the eelworm pathogens, except one makes use of hybrids.
Hold information
In accordance with Mugerwa, conserving a file of farm historical past is a good assist in remembering which crop has previously been grown in a specific plot inside the subject or farm.

That is helpful particularly if the information additionally present previous incidents of plant pests or ailments in every plot within the farm. He advises one to divide the farm into small models to facilitate advert hoc placement of crops onto fields every year.
By this implies, cropping historical past of each a part of every subject is straightforward to take care of as drawback plots will be simply recognized.

Guiding ideas
Within the rotation of crops, Mugerwa says that the final precept is for leguminous crops equivalent to pulses, beans, peas, groundnut and inexperienced gram to be grown after cereal crops like wheat, maize and millet.

“When the cereal crops equivalent to rice, wheat and maize are grown within the soil, it makes use of up lots of nitrogenous salts from the soil. If one other cereal crop is grown in the identical soil, it turns into nitrogen poor,” he says.

So by rotation, a leguminous crop has the flexibility to repair atmospheric nitrogen to kind nitrogen compounds via the assistance of sure micro organism current of their root nodules.

These nitrogen compounds go into the soil and make it extra fertile.

Mugerwa provides that exhaustive crops (crops which feed closely on the soil and deplete soil vitamins) equivalent to potato, sugarcane, sorghum, tobacco and sunflower, needs to be alternated with much less exhaustive crops like oilseeds and pulses to revive the fertility of the soil.

“The continual cultivation of exhaustive crops in the identical land results in gradual discount of soil fertility or nutrient standing of the soil. Subsequently, restorative crops whose root nodules within the roots repair atmospheric nitrogen into within the soil are ultimate alternates,” he says.

He provides that legumes equivalent to alfalfa, peas, beans, lentils, soy and peanuts shed their leaves whereas reaching maturity which provides extra vitamins to soil.

In case of the faucet root crops like beetroot and carrot, they need to be grown alternately with fibrous root crops for uniform utilisation of soil vitamins.

On sloppy lands, Mugerwa says, alternate cropping of abrasion selling and erosion resisting crops needs to be adopted.
He says that rotations with alfalfa and different legumes scale back fertiliser wants as a result of these crops substitute a few of the nitrogen eliminated by maize and different grain crops.



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