8 best practices to eliminate weeds in Conservation Agriculture method

Conservation agriculture is a new method of agriculture which avoids the conventional methods of tilling the land before sowing the seed. Instead, it focuses on minimal soil disturbance and retention of residue to keep the moisture of the soil and to avoid erosion of manure and herbicides.

Maize under Conservation Agriculture in Malawi
Photo courtesy CIMMYT

 However, a major issue with the method is the presence of weeds. Following are some of the best practices to avoid weeds in conservation agriculture. However, they are modified to meet sustainable agricultural practices.

The methods avoid chemical herbicides as they cause environment pollution and turn less effective in long term.

1. Prevent weeds

·         Prevention is always better than herbicides. So make sure that you use clean crop seeds and machinery for seeding, harvesting and threshing, since many weed seeds actually reaches the seed bed in this way.

·         Keep field margins and irrigation canals free from weeds.

2. Stale seedbed techniques

·         Irrigate the seedbed lightly in advance so that the weed seeds which are often found in the soil surface germinate in two three days. Once they germinate in this period, first clear them off manually or using organic herbicides.

·         It is also advised to encourage seed predator insects or birds in the seed bed before sawing.

3. Adjust time of crop sowing

·         Make the crop sowing early in the season so that the crop gets a competitive edge over late germinating weeds.

·         This method has been proved successful in North India against certain weeds like Phalaris minor (Red Rice) when wheat crop was sowed early in the season.

4. Grow a cover crop which gives thick mulch

·         Grow crops like cowpea or sun hemp, which will produce thicker residue, between two main crops. Then cut down it before the main crop season.

·         The dead mulch of the cover crop not only helps retaining the moisture of the farm land, it also suppresses the weed germination by releasing allelo-chemicals and blocking sunlight which is needed for the seeds to germinate.

5. Use of narrow row spacing

·         Place crop rows closer so that they grow thicker, often blocking the sunlight to the space in between two rows, thus decreasing the chances of weed growth in between two consecutive crop rows.

Ground nuts under Conservation Agriculture
Photo courtesy CIMMYT

·         The space between two rows is a vulnerability of the conventional method which actually helps weeds, especially in maize and soya bean cultivation. Narrowing the gap between two consecutive rows can control weeds to a great extent.

·         15 centimeter row spacing is found very successful against P.minor.

·         Long term adoption of the method will bring down the availability of viable weed seeds in a seed bed.

6. Higher seeding rates

·         Increased crop density sometimes helps the crops compete better against weeds.

·         Higher seeding rate is proved to help in weedy or partially weedy seedbeds, though the method may not bring good yield in weed-free environments.

7. Use of weed competitive cultivar

·         The wild or traditional seed varieties which produce long shoot plants are more weed competitive though their yield is not on par with the short stature, high yielding modern seeds.

·         A continuous use of conventional weed-competitive cultivars coupled with narrow row spacing and other methods will bring down the weed presence and number of available weed seeds in a seed bed considerably if the farmers are ready to afford the decrease in production during a short term.

8. Adopting crop rotation

·         Crop rotation helps decrease certain crop specific weeds like P. minor in the case of rice or wheat crops.

·         Rotating the rice crop with a non-rice crop like maize or soybean can disrupt the lifecycle of such weeds.

·         Rotation the management practices also disrupts weed life cycle.

·         Crop rotation improves the soil quality too.

These methods are proved as effective weed management methods in conservation agriculture practices. Many of them are effective in other types of agriculture practices too. However, anyone of these methods when practiced alone may not bring a good result in eliminating weeds. But a brilliant coupling of different methods will surely produce a good result.

If you know any other weed management methods, share it for our readers in the comments.

Reference:
 Chauhan, B. S. & Mahajan, G (2012), Role of integrated weed management strategies in sustaining conservation agriculture systems, Current Science Journal, Volume 103, Issue 2, July 25, 2012, Indian Academy of Sciences, Bangalore, Retrieved from http://www.currentscience.ac.in/Volumes/103/02/0135.pdf on July 25, 2012.