Lucerne does it need special treatment and should you rest it in autumn

There is plenty of anecdotal evidence by lucerne growers to suggest that it is beneficial for a lucerne stand to be ‘rested’ before the first autumn frosts to increase yield and persistence as well as the health of the plant.

A trial conducted by Meredith Mitchell of Agriculture Victoria in Rutherglen in 2016⁽¹⁾, looking at testing some guidelines in regards to defoliation vs the length of recovery period in winter active 7 lucerne and whether that affects persistence of the stand. They weren’t taking into consideration the percentage of flowering in the trial, as that can be subjective, so they looked at four main systems: short rest (SR - 3 weeks post graze); long rest (LR - 6 weeks post graze); new shoots from crown grown to 2 cm post graze (NS) and new shoots from crown grown 2cm post graze + a prolonged rest from late summer to flowering near autumn break (NSF). They measured persistence, herbage mass and taproot mass in established winter active 7 lucerne stands at two Victorian sites in November 2014 to June 2016.

Their results indicated that a six-week recovery period maintains maximum lucerne productivity⁽²⁾ and persistence which in a practical on-farm situation; could mean better long term dry matter yields and persistence with ease of management without a subjective assessment of new shoots.

So it seems from both this trial as well as other lucerne producers, lucerne does perform better and benefits from a decent rest during the autumn period; but I thought I’d ask one of my lucerne hay producers in the Maitland area of NSW, Thomas Woods from Heatherdean Produce, for his opinion on whether lucerne requires as an autumn break as well as what he does to produce some of the best hay in the Hunter Valley. The following is a transcript of my interview with Thomas prior to Christmas.

AWS: What level of irrigation would you suggest with your newly sown lucerne?

TW: First time on dry ground you need 25 mm of water, then follow up within 7 days by irrigating again with about 20 mm. From there, it will probably be right for about two weeks, then you’ll have to water again once its reaching the first trifoliate leaf stage just to keep it growing. You don’t want to stress the plants out in the young stage as the seedlings will drop off, you want to keep them growing actively and healthily and have enough moisture that they can put their roots down and bear roots in a healthy growth stage.

AWS: With your nutrients, you mentioned before that lucerne does sap a bit out of the soil so what nutrient levels are you looking at and do you soil test?

TW: I don’t soil test regularly, but you can tell from the lucerne itself just by looking at it if you know what you’re looking for. If your lucerne starts to develop a darkish, bluish colour in the growth stage, your lucerne is lacking in phosphorus (P). If it starts to get little white tips on your leaves then youre short of potassium (K). Yellow spotting on the leaves is a deficiency in sulphur (S). So in general terms if you are getting 100-125 bales to the hectare, you know you’re going to have to put back in 150 kg every two months of something like sulphate of potash which puts S and K back in. Then maybe once every 6 months an all-round fertiliser, like Multigro, which supplies your trace minerals like calcium (Ca), Molybdenum, etc., which does help lucerne. If youre lacking in Ca or other trace elements, that’s your limiting factor of growth, just like a bucket with a hole in it. I’ve done trials of my own in various paddocks and where I have applied the trace minerals, and where I haven’t, you see a big difference in growth in the lucerne.

AWS: You mentioned that you broadcast your lucerne seed onto the prepared soil bed, what sowing rate do you use?

TW: I always sow quite heavy because I find that the lucerne, if you put it on heavy, will thin itself out naturally and you’ll end up with the strongest seedlings possible. If you put it on at the correct rate, or less, and it turns a bit dry, or your irrigation is a bit uneven and you get seedling dieoff, then you’re already behind the 8-ball to start off with. When it’s a 3-year plus investment, seed is the cheapest part. If you’re getting six cuts per year and 125 bales/ha, it’s 750 bales/ha/yr so the seed is the cheapest part. So, 40 kg/ha on irrigated ground is what I run at and I think the normal rate is 20-25 kg/ha and obviously if you don’t have irrigation then you don’t put it on that heavy as your ground can’t sustain the growth in very dry hot periods and it will stress the entire crop.

AWS: How do you control any weeds or is it just that plant numbers will crowd out any weed burden?

TW: Weed burden occurs when growers plant lucerne after lucerne, as you get a build up of chemical tolerance from certain chemical groups. For example, everytime you spray, you don’t kill every weed and those weeds with their seeds will get a tolerance, almost a resistance to the chemical. Having a break crop helps because you’re knocking out weeds using different chemical groups and you’re continuously turning your soil. I like to spray my lucerne coming into spring with Sprayseed® and that will get rid of any new broadleaf weed seedlings and new grass growth. But the higher plant numbers you have in the paddock the easier it is to smother out the weeds. But I do try to minimise the amount of chemical I use because it does cause some retarding of lucerne growth, but with a healthy crop and high plant numbers you won’t have much of a problem with weeds anyway.

AWS: When it’s a healthy crop, how much of an issue are insects?

TW: They’re not. I had this debate with my neighbour recently as he was getting leaf roller and I wasn’t. He asked why I don’t have any issues with this and he does? I said because my lucerne isn’t stressed! If you’ve got a healthy crop and you’ve kept the fertiliser on it plus moisture up to it, which allows it to grow at a constant pace, the insect pressure is very minimal so you’re saving on chemical sprays there too.

AWS: With the break crop that you use, I guess that would help with keeping everything healthy too?

TW: Yes it does, absolutely. With the break crop, you’re changing over all your chemical imputs as well, so the ground is freshened up and that first year the growth that you get virtually requires no fertiliser and not much spraying because its new ground pretty much. So we’ll use our vegetable crops (potato, pumpkin or cabbage) for 1-2 years then I’ll sow lucerne back into my vegetable paddocks as there’s a lot of excess fertiliser left over from potatoes, plenty of moisture in the soil and with pumpkin you get a large canopy of green leaf to chop back in. Plus they put so many feeder roots into the soil that really aerates the soil to break it up and it’s a completely different crop to lucerne so you’re breaking that disease cycle. The lucerne will love the fresh soil and the vegetables will love the excess N that the lucerne has put into the soil.

AWS: If you were a general farmer that was using lucerne, there’s some evidence that shows that resting lucerne in autumn is beneficial, what are your thoughts on this? 

TW: If lucerne was my main game, which it has been in the past, I would feed it going into winter and that allows it when it comes out of winter into spring, to have that head start because you already have those nutrients in the soil. I would cut it off in autumn, then feed it but you should allow it to go to flower at least once a year, and I would recommend that in winter to reduce stress on the plant because when it goes to flower its turning excess carbohydrate from the top of the plant back into the roots, which help build up the energy levels in your root reserves. If you cut your hay too often it will slowly and surely deplete the energy levels out of your root reserves and you’ll find your lucerne will struggle to come back. It will come back more stressed each and every time. So, I believe that’s when the natural cycle of resting should occur during that period from autumn – spring.

AWS: So, you’ve been using our Titan 7 lucerne for over a year now, how have you found that has performed for you compared to other varieties that you have used?

TW: With our intensive lucerne production here in Maitland, our main goal is to produce high quality hay, and we’ve tried a lot of varieties, but the Titan 7 is up the top of my list. It produces a very fine stem, even if you irrigate it a lot, which a lot of varieties, like L56, won’t do. You get the yield off L56, but it produces a very thick, stalky stem on irrigation or not. Whereas with Titan 7, even if you irrigate it really hard, you’ll still tend to find especially in the first few years, it’ll have a really fine stem which produces leaves from the top to the bottom. Leaf is an important thing, because in the horse area especially, all the protein is in the leaf, so the more leaf you can have the better quality hay you’ll have. Its about always trying to produce a better bale. The Titan 7 retains its green colour really well, even if its had a few ‘bleach’ days from foggy mornings etc., so overall for an intensive lucerne, for a lucerne for a high end use, Titan 7 fits the bill – for its higher stem/leaf ratio and its ability to stay green in the bale.

AWS: You mentioned the protein levels in the horse hay before, do you ever measure your protein and moisure levels in your hay?

TW: I have measured it once before and it came out about 22% protein but I had put fertiliser on the Titan 7 just before that too.

AWS: During the past couple of years, the Maitland area has received some substantial rainfalls,although not this year, how has Titan 7 dealt with waterlogging during those massive rain events?

TW: It handles it really well. I had a paddock of lucerne at my other farm that wasn’t Titan 7, which got really stressed from waterlogging, in comparison to that paddock which was right beside the Titan 7, the Titan 7 “outgunned it” the whole way. It didn’t lose many plants except in one spot where it was completely underwater for about 3-4 days and even in that situation, I only lost around 20% of that patch, so it handles waterlogging really well and its ability to hold on works really really well.

AWS: I have one last question Thomas, overall what’s your perception of Titan 7 and would you recommend it to other lucerne growers?

TW: Yes I definitely recommend it. With its ability to hold on during dry times it is pretty good; it produces a good top of the range bale of hay to sell to your customer and in terms of planting, its ability to get up out of the ground and get a good strike rate, is exceptional. So yeah, I’d recommend it to anybody wanting to grow lucerne.

Note: Farmers words/options are his own. For our advice on sowing lucerne please visit: https://www.ausweststephenseeds.com.au/Advice/Planning-and-Preparation/Lucerne  

References:
(1) http://agriculture.vic.gov.au/agriculture/livestock/sheep/sheep-notes-newsletters/spring-2016-sheep-notes/lucerne-grazing-management-is-easy
(2) http://agriculture.vic.gov.au/agriculture/livestock/sheep/sheep-notes-newsletters/spring-2016-sheep-notes/lucerne-grazing-management-is-easy; cumulative herbage mass of lucerne DM kg/ha chart, page 4