Sustainable Farming: Use of Cover Crops
For us farmers, weed management remains an arduous and challenging task that we cannot avoid. Most often weeds account for 60-70% reduction in crop yield for farmers. Naturally, in the short term, using herbicides is one way to manage weeds in a cost effective manner. However herbicides come with their own hazards, and we are all familiar with court cases in the developed countries accusing Monsato’s Round Up of being carcinogenic ( i.e having potential to cause cancer). Apart from human health impacts, persistent use of herbicides creates ground water pollution, reduces organic soil matter content, and degrades the soil. In the long run, this leads to increased use of production inputs such as fertilizer and pesticides in the farm.
At Pinewood, we are focused on seeking alternatives to manage weed while producing cost effective and healthy food. So we have started experimenting with the use of cover crops. Working with experts in crop production we planted some cover crops on our land. The results have been quite interesting:
- Two experimental fields (each field about 5ha) was densely planted with 4 different crops. The 4 crops were used as cover crops and consisted of plants in the grass (cereals), legume and herbs families. For the first time since we started farming we saw no significant pest presence on our farm during the planting season ( in fact our stock of neem oil is largely unused). Additionally, in the fields where we intercropped the 4 cover crops we only had to do one weeding. We are nearing harvesting, and clearly the one moment of weeding was enough to significantly reduce the presence of weed in the fields.
- Three fields were fallowed to two different cover crops. In each field, weed presence was also significantly reduced.
We chose our cover crops very meticulously. Doing our own research, and combining this with input from crop experts, we planted Mucuna Pruriens and Prueraria Phaseoloids in the farm. This is a summary of the key things we know about each cover crop. We encourage you to do you own research. There is a lot of information about cover crops on the web simply type in cover crops in google to start educating yourself.
Preparing to plant
To kick off our planting/experiments, we did land preparation before planting. We ploughed the field and planted. In the experimental fields, erosion was significantly lesser than in fields where we planted cassava.
In the coming farming season we will continue with our experiments on cover crops. However given the significant erosion we saw after ploughing, we will not plough in the 2020 farming season. We will either harrow or use a CRI for the land prep. This is in continuation of our efforts to determine the best land prep method that delivers the best impact for our soil. We are also trying to ease out of ploughing because of the significant erosion issues we experienced last year. This is in comparison to 2017 when we used a CRI. In 2017 erosion issues were less but we had significant weed challenges. In 2020 we will combine CRI with cover crops and closely monitor the impact on erosion and weed presence.
What we planted
Prueraria Phaseoloids ( Tropical kudzu)
Pueraria improves soil nutrient availability, stimulates soil biological activity, and controls soil erosion, leading to high soil productivity. It has been known to fix 150kg to 200kg of N into the soil. Pueraria roots can grow to 2m, allowing the crop to survive 5 to 7 months of dry season. Pueraria fallow reduces the decline of soil organic matter under cropping and increases N concentration in particulate soil organic matter. It is a very effective weed suppressor. It is also a palatable food source for grazing ruminants. You can broadcast it at 10kg/ha or seed it at 8kg/ha. It is a slow grower but a perennial plant so the best weed suppression benefit will occur in the 2nd year after planting.
We used it in the fallow capacity in 2019 and did not weed the field. We could already see the weed suppression impact on that field. We will be monitoring its weed suppression impact in the 2020 farming season and share our findings as a continuation on this blog.
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Our best field experiment was with the Mucuna field. It is an amazingly fast grower, establishes within 4 weeks, climbs everything in its way, and weed suppression is delivered almost within the first 6-7 weeks. We did only one weeding at about 4 weeks after planting.
Mucuna is considered to have 3 main uses: food, feed (forage and seeds) and environmental services. For 2019 we focused on using it for environmental services. In the coming years we will be exploring the food and feed uses as well.
Benefits as environment services: Main environmental impact is as a cover crop and as a soil improver. It is capable of fixing about 300kg N/ha and yielding 100kgK/ha and 20kgP/ha. In intercropping situations, it acts as a biological control due to its pest and disease resistance (refer back to our experience of no significant pest instances in our farm this year). It has been used in experiments in South America to reclaim land infested with Cynodon Dactlyon, Cyperus species, Saccharum spontaneum and Imperata cylindrica. It is also recommended for use in rotation with cotton to limit Fusarium oxysporum infestation. It can also effectively control nematode infestation by species such as Meloidogyne incognitat.
You can intercrop it with maize, however you should only plant it 4-5weeks after planting maize. It should be planted at a planting rate of 35-40kg/ha.
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