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Vleis - 1 - Module 2: Soil and water management

A GROUP EXTENSION GUIDE USING PICTURES

ALTERNATIVE SOILAND WATER AND WEED MANAGEMENTSYSTEMS FOR VLEIS

with emphasis on maize-rice systems

MODULE 2: SOILAND WATER MANAGEMENT FOR VLEIS

This is the second of 7 training modules

Vleis - 2 - Soil and water management

Options for crop and soil and water management for wet and dry vleis

A number of options are available to farmers for summer cropping maize and rice.This depends on the resources they have available. These are summarised in thefigure below and detailed in the following sections of this booklet.

Vleis

Dry vleis Wet vleis

Maize Maize-rice Rice Maize Maize-rice Rice

Plant onflat

Beds orfurrows at

1st weeding

Beds, ridges orfurrows at first

weeding

Planton the

Flat

Notrecommended

(high risk)

Beds, ridges orfurrows at first

weeding


??


This is typical farmer practice, where maize is planted in every third furrow during normalploughing. In between the rows of maize, rice can be either broadcast or sown in rowsparallel to the maize rows. Some farmers plant the rice in the same row as the maize, whichallows easier weeding through the season.

ExplainThe main weakness with this technique is that the maize can be adversely affected bywaterlogging, even if rains are only moderate. Whole areas are often abandoned ifwaterlogging and/or the weed burden has become to great.

Advantages

Good germination under dry conditions Less labour required compared to beds or ridges This can be the best method for planting maize

on dry vleis. Farmers can retain the flexibility toconstruct post plant ridges or furrows if the sea-son becomes wet

Disadvantages

Maize can be adversely affected bywaterlogging

Picture SWM1: Farmer ploughingQuestion: Do you recognise what this picture is?

Answer:


Picture SWM2: Farmer making post-plant ridgesQuestion: Do you recognise what this picture is?

Answer: This is a farmer making ridges with his plough after the crop has established and is activelygrowing. Discuss the advantages and disadvantages of pre-plant ridges

ExplainThis system is similar to pre-plant ridges, in that they are designed to move excess water away from thecropped area. However, the main difference is that the ridges are constructed AFTER the maize crop hasemerged. Maize is first established on the flat, andwhen thecrop is at knee-height the ridges are constructedaround the base of the maize plants using a plough. This has the dual function of controlling between-rowweeds and removing excess water. The system works best with sole maize. Rice can be sown in the samerow as maize, but this presents problems for timing of ridge construction – if done too early, the rice will besmothered by the soil moved by the plough; if left too late the maize will be too large to allow the animals intothe crop without causing damage. It may also be too wet to get into the field with the cattle.

Advantages

Planting on the flat means that germina-tion is not a problem when conditions aredryExcess water can be removed from the

cropping areaBetween row weeds can be controlled at

furrow construction

Disadvantages

Unsuitable for a maize-rice intercrop as rice issmothered at ridge construction

May be impossible to construct if field becomes toowet

If ridge construction is left too late, the maize cropwill be too tall to allow cattle to work without damage

The maize rows must be graded correctly


??


Advantages

Maize on the ridge is not affected by waterloggingand rice will thrive in the furrows

Fertile topsoil is gathered on the ridge benefiting thecrop

Ridges reduce soil loss if graded correctlyGood yields can be obtained in a wet seasonRidging increases rooting depthRidges can be rebuilt at weeding using the plough

Disadvantages

Reduced moisture levels on the ridges cancause germination problems

Initial labour requirement can be highRidges need to be pegged by someone

who can use an A frame or line levelIt is difficult to control weeds on the ridge

using a cultivator

Picture SWM3: Farmer making pre-plant ridgesQuestion: Do you recognise what this picture is?

Answer: This is a farmer ploughing and making ridges before the crop is planted. Discuss the advantagesand disadvantages of pre-plant ridges

ExplainThis system involves the use of ridges (ideally about 25 cm in height). These are laid in the field at a grade ofbetween 1:100 and 1:250 across the slope. If dry conditions persist, cross-ties should be constructed to aheight of half or two thirds the height of the ridges at intervals of 1 to 2 metres, depending on slope. The ridgesare constructed using an animal-drawn plough or ridger in a deeply ploughed field. Just like broad beds, ridgesreduce the impact of waterlogging on crops like maize while allowing rice to be grown in the furrows..


Picture SWM4: Farmer making broad bedsQuestion: Do you recognise what this picture is?Answer: This is a farmer ploughing and making beds. Discuss the advantages and disadvantages of bedmaking

ExplainThe system consists of broad beds and wide furrows. The beds should be approximately 1.2 m wide andthe furrows should be 30 – 45 cm wide. In the event of there being below average rainfall, cross-ties canbe constructed at intervals along the furrow to stop run-off.

Crops that are sensitive to waterlogging, like maize, are grown on the bed whereas those that can withstandexcess water in the rooting zone such as rice are planted in the furrows. The system is designed so thatthe two crops are able to thrive in the same environment. Water captured in the furrows and cross-tiesmade during dry spells can also benefit the crop on the raised bed.

Advantages

Maize on the bed is not affected by waterloggingand rice will thrive in the furrows

Fertile topsoil is gathered on the bed benefitingthe crop and increasing rooting depth

Beds reduce soil loss provided they are gradedcorrectly

Good yields can be obtained in a wet season

Disadvantages

Reduced moisture levels on the beds cancause germination problems

Initial labour and draft requirements can behigh

Beds need to be pegged by someone whocan use an A frame or line level

It is difficult to control weeds on beds using acultivator or plough


Disadvantages

If left too late rice will not fully matureCan cause erosion if the slope is not

graded correctly If heavy rain falls it may be too wet to

make furrows

Picture SWM4: Farmer making furrowsQuestion: Do you recognise what this picture is?Answer: This is a farmer making furrows after the crop has established.ExplainFurrows can be used in wetland systems to assist in draining the excess water away from the croppedfields to the waterway. They are simply created by ploughing between the crop rows with an animal-drawn plough but they must be graded correctly to avoid erosion (1:100 to 1:250). They can be usedin two circumstances:1 Some farmers use temporary drainage furrows before planting to remove excess water from the

vleis so that they are able to get in to the fields to plough and plant.2 A second method is to create the furrows after planting, mid-season. Maize is sown on the flat, using

the third furrow technique, and once it reaches knee height, furrows are constructed in alternate rowsto remove the surplus water from the cropped field. Rice can be broadcast in the furrows, althoughas with post-plant ridges, the timing of construction is very important. If the furrows are left too late,then the rice will not be able to fully mature in the remaining part of the season. As with post-plantridges, the creation of furrows also has the benefit of controlling between-row weeds.

Advantages

Planting on the flat means that germination isnot a problem when conditions are dry

Excess water is removed from the croppedarea

Between row weeds can be easily controlled

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