Moisture availability is important. Deciding on a suitable soil regeneration or maintenance strategy – especially in the summer rainfall regions of Africa – needs to be given a great deal of thought and planning, should you want to adopt and succeed with a winter cover crop regime. No-Till enthusiast J. P. Van Reenen tells about his experiences.
The KwaZulu Natal No-Till Club has been operating for 20 years. According to Richard Findlay, the coordinator of the No-Till Club, the importance of using cover crops in a rotation programme between annual crops has been receiving much attention.
Cover crops are catalysts in soil regeneration as they increase soil cover, helping to minimise wind and water erosion. In addition, they increase water infiltration into the soil while at the same time reducing evaporation. Cover regulates the soil surface temperature marginally, by increasing soil temperature in the cooler months and reducing it in the warm months. All these attributes make it more pleasant for the essential microbes, insects and earthworms to want to stay and regenerate while maintaining a healthy fertile and productive soil.”
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One of their most enthusiastic members, J.P. van Reenen, was only a youngster when it started. He farms in the Bergville District of KwaZulu-Natal and is a No-Till enthusiast who does a lot of study and research and is not afraid to try different techniques and systems.
“I’ve been experimenting for 3 years now, concentrating mainly on inter-row cropping. On a centre pivot I’ve planted 50 ha. I plant 2 rows in-between my maize, basically a Stooling Rye mix, the Stooling Rye has worked the best. Other things I’ve planted include clover, which didn’t really work, it came through a bit and then more later in the spring. This year I’ve put a bit of sun hemp in and I’ve put in some cow-peas as a companion crop.”
“I modified my John Deere planter with an APV seeder unit originally. I relocated the fertiliser coulters (double-disc openers) to an extra toolbar. I’m quite happy with how this is working. In the beginning I started with 3 inter-rows, but the trash was too much for this to handle, it kept clogging up.”
“This year I have extended it so it now plants 16 rows. The rear depth wheels also act as press wheels, but I think I will add a little chain behind the coulters to help cover the seed. Every year I seem to add a bit more refinement. When I originally checked the price of proprietary units, the cost was prohibitive, especially as we were just testing theories, so I decided to use available parts to construct our own unit.
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“Last year I left the cover crop in a bit too long, where the cattle where grazing. Sprayed it off a bit late and, with no rain, lost a lot of moisture. Timing is critical and heavily dependent on when the rain comes. When the following maize germinated the areas, which had had the cover crop showed signs of moisture shortage. Because of this a lot of people are speaking negatively about cover crops, but you can’t change your farming system because of one bad year.”
Looking at farming 3 years ago, I realised that the biggest factors are my input costs, chemical input costs in particular. My aim in the next 5 years is to try to get away totally from these high inputs. I know that some farmers locally are up to about 300N on their irrigated maize, I’ve been at about 220N. This year I’m on about 160/170N and walking the lands, now that the maize is tasselling, I haven’t picked up any nitrogen deficiency. These lands have had two leguminous crops before on the irrigated lands. Soy beans and then peas in the beans. In the next few years I want to see if I can cut down on fertiliser.”
J.P. van Reenen:
I realised that the biggest factors are my input costs, chemical input costs in particular
This year, on all my plant mixes I looked at what I would have spent, rand/hectare on fertiliser; this would have been about R1 800/ha, that would be for N, P and K but it’s not only those elements that matter, I understand that there are in fact about 74 different elements and nutrients but we only rely on 3 and think that is going to sort everything out.”
“When I looked at my soil samples, I found they were all short of Manganese, Zinc, Boron, Sulphur and other trace elements so I took my Potassium Chloride out to avoid putting chlorine in the soil, and went to Potassium Sulphate, MAP (Mono Ammonium Phosphate), manganese sulphate, copper sulphate, boron and zinc sulphate. I made a mixture for that same R1 800, which ends up at about 10N, 22P and 22K. Most people will say that’s not enough, but I’ve been doing it for the past 2 years and I’m still getting good results, and my soil samples where I’m doing the cover crops are good.”
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The biggest thing that scared me, was that when I took my soil in for sampling, they reckoned that I needed to put 280kgs of MAP over the whole farm. I said that is going to cost me about R2 million, I can’t spend that kind of money. So, I’m now looking at compost to bump up the phosphorous in the soil. I’m looking at the compost route to bring the biological features back.”
“I have a supply of manure from a local feedlot and I put it in piles to make compost and add hay to try and get the carbon/nitrogen relationship right. Initially I will try to spread 5 tons/ha and at the same time I am trying to increase my earthworm population so I will feed compost to my earthworms to make vermicast and then spread 2 tons/ha of vermicast to give the land more biological power.”
This is where the cover crops come in, you can add organic matter, but you can also create your own organic matter. So, I’m trying a lot of things and in 5 years’ time I may have got the whole cover crop rotation right, then I won’t have to rely so much on compost. I just want to use it as stepping stone in the beginning so that I can get my soil to a point where it becomes self-sustainable.”
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“I have just been through the lands and I think we will only have to spray fungicide once instead of the usual 3 times, this may be down to the previous cover crop. One school of thought is that fungicide is counterproductive when you are trying to get fungi to work in the soil to enhance it. You’re trying to get the beneficial fungi growing in the soil and spraying may be killing them off.”
“After a lot of reading and study online, I’m also thinking of planting a 5 ha block of maize on 60” rows with a summer cover crop in between. We currently plant at 30” so I will block every other row as a trial. Research in the States has shown a very low yield lag with this type of cropping. I will plant a mixture of cow-peas, sun-hemp, and beans, maybe even add some squash. Maybe there is synergy between the roots? I may only grow 10 tons/ha but if I use less fertiliser and very little spraying, it should still show a good return. It will certainly be a more peaceful life that having to jump up and spray all the time.”