Soil nutrition
Soil nutrition key to future profits
This case study has been made available on-line thanks to funding under the Australian Government's Eco-efficiency Agreement.
Tom Loeskow is building the soil fertility on his farm for the next generation. Recent soil tests are proof that his farming methods are paying dividends, but it has been years in the making.
Two years ago Bundaberg grower Tom Loeskow intended to plough out a block of fifth ratoon cane but for some reason he didn't get around to it. He has since cut two more crops from this paddock and achieved 50-60 tonnes to the hectare and above mill CCS from these old ratoons, grown without any fertilizer, chemicals or irrigation water.
A soil test taken on this particular block gives a satisfactory rating for all tested nutrients, and the same results are coming in from blocks all around the farm, says Tom. "You can't get better than that and there is no reason why it can't be maintained."
Tom believes that twenty years of green cane trash blanketing is the key to the current soil fertility levels on his farm.
Over recent years Tom has decided to get back into green manure crops. He is currently trailing a mix of field pea and turnip as a winter green manure crop. "The field pea is to fix nitrogen and the turnips have soil fumigant qualities, says Tom. To my knowledge, no one else in the area is growing winter green manure. I hope to develop a rotation using a summer green manure crop like cow peas or soybean followed by a winter green manure crop like turnip and field peas then back to cane in the following Spring."
Tom's current farming system involves discing the old ratoons in February and broadcast sowing the seed for the winter green manure crop. The seed is lightly disced in and the old cane stools provide good surface cover while the seeds germinate and establish. By the time the green manure crop is ready to turn in the cane residues are brittle and easy to work. To prepare for the spring-plant cane, Tom will disc, rip and rotary once before planting.
The summer crop will be grown with the intention of harvesting grain if the opportunity presents itself, but Tom's real aim is to break the grass cycle, reducing soil pest populations and reducing the need for nitrogenous fertilizers in the following cane crop. "If the season is favourable I will row crop the summer legume so I have the option of harvesting the grain," says Tom. "Under these circumstances I will plant the crop myself and have it contract harvested."
Off-farm education has been a priority for Tom throughout his working life. He started with an agriculture course at (then) Gatton Agricultural College and later a management course through the Rural Management Development Centre.
More recently Tom identified accounting and efficient farming skills as his two main training priorities. To this end he decided to attend a COMPASS course to discuss best management practices with industry advisors and other growers. "The COMPASS course made me aware of a few things that I have not been doing but generally confirmed that the farming system I have in place is efficient and working well", says Tom. "There were some sessions that were not directly relevant to me but they still posed some 'what if' questions that made me think beyond my current situation."
In the key areas of irrigation, soil fertility and chemical use Tom found that his current farming practices are in line with the best in the industry.
Irrigation
Tom uses subsurface trickle, winch and flood irrigation methods on his farm. "All my irrigation decisions are based on likely return on investment," says Tom. Water is a very limited resource and is applied sparingly, concentrating on blocks that are most likely to produce the greatest return.
About 20 percent of the farm is red soil and this is where the subsurface trickle tape is installed. When irrigating, Tom monitors the soil, checking for when field capacity is reached. Field capacity is the point where the soil has absorbed all the water it can hold before it begins draining away from the root zone. "I do three or four random tests around the paddock," says Tom. "All you do is take a lump of soil from around 20 cm away from the tape and make a ball with it in your hand. If you can make a ball that sticks together but does not make your hand muddy, then the soil is at field capacity."
The remainder of the farm is brown clay loam topsoil over a clay subsoil and Tom has had all these blocks laser levelled to improve flood irrigation efficiency. When the cane is small it is irrigated by winch with a tapered nozzle attached to reduce the formation of small water droplets. "I only winch at night so losses to wind are minimal and the water has time to infiltrate into the soil before sunrise," says Tom. "Once the cane is out-of-hand I start flood irrigating."
The clay is around 45 cm below the soil surface so these soils are well suited to flood irrigation. The 0.035 percent slope on some blocks means the water flows well down the rows but there is also significant lateral, underground movement of water. "Having less control of where the water goes makes it important to have a water recycling system in place," says Tom. "About 2.2 km of drainage lines run through and around the property, collecting runoff from the blocks and the surrounding catchment. The water flows around to the low point where I can pump the water out again for irrigation."
Tom flood lifts water from a second recycling sump into a 150 ML turkey-nest dam. A catchment area of around 400 hectares drains into the retention pond via grassed drains. When the turkey-nest dam is full, Tom can gravity feed water to blocks up to 1.75 km away for flood irrigation, saving a small fortune in pumping costs.
The choice of water application method is only part of the story though. Tom also puts considerable thought into what source of water to use in different circumstances. "I use some of the dam water first to maximise the chance of refill events," says Tom. "In March I start on the surface and subsurface water to use my allocation."
In keeping with his return on investment philosophy, Tom gives his plant and first ratoon crops highest priority when making irrigation decisions. The red soil also receives favoured treatment due to the inherent productivity of the soil and the investment in trickle tape. "Some of the farm doesn't get watered and yet these blocks of older ratoons can still turn out to be quite profitable," says Tom. "If no irrigation, fertilizer or chemicals are used to grow a crop even modest yields can turn a profit."
Soil Fertility
Tom conducts soil tests every time a block is ploughed in and consults with BSES and fertilizer company agronomists to determine the best products and application rates. "Over the last ten years the fertilizer rates required have been declining," says Tom. "Ten years ago I was applying 687 kg/ha of Crop King 140S to my ratoon cane. Now I only need to apply 562 kg/ha of Crop King 140."
This reduction in fertilizer required not only represents a great cost saving but proves to Tom that he is building soil fertility through his green cane farming system.
Trace elements are not needed on Tom's soil types but lime applications are needed every crop cycle. "The lime seems to be needed to balance out the acidic fertilizers," says Tom. "The closer we can get to natural production systems the better."
Tom chooses to apply fertilizer with a stool-splitter so that the applied nutrients are kept close to the root zone and out of the inter-row space. He has been using this application method for over ten years and is very pleased with the results.
Maintaining structural fertility of the soil is also important to Tom. He plants his cane in 1.63 m wide centres, single rows and has no intention of moving to wider row spacing. "I am not in favour of zero tillage on some of my soils," says Tom. "These soils respond to deep ripping of the inter-row space because compaction of the inter-row reduces the water infiltration and water holding capacity of the soil."
Tom believes that farmers should seriously consider whether harvesting wet blocks is economical or not. "It is the farmer's decision and it is worth thinking about the long term damage caused by a wet harvest," says Tom. "For me, leaving a block to stand over is more economical than increasing the row spacing to allow for a wet harvest, particularly with a climatic trend toward drier harvest seasons."
Chemical Use
Tom does his best to minimise the use of chemicals for pest and weed control. He uses knockdown herbicides to control grass and vine weeds in ratoon crops and residual herbicides in plant cane.
Each block is treated differently according to the age of the plants, organic matter levels in the soil, lime applications and soil structure. Fresh organic matter, lime and cloddy soil all reduce the effectiveness of residual herbicides and insecticides so Tom avoids applying these chemicals unless the conditions are favourable for maximum effectiveness. Tom has also changed over to low drift nozzles on his boom spray to reduce the chance of spray drift.
Tom uses IPM to reduce the amount of pesticide applied on the farm. "Cane grubs and some soldier fly are the only major pests that need treatment here," says Tom. "I rely on cultural practices or cultivation and green cane trash blanketing to keep the populations under control."
Tom applies SusCon at planting on the red soils only and monitors stool damage to determine if isolated areas need additional treatments. Tom believes that improving soil fertility is the key to promoting a balance of beneficial and pest species in the soil.
A business-like approach to farming and a desire to develop a farming system that builds natural soil fertility is the key to Tom Loeskow's long-term success. He is also working hard on the accounting side of his business, including the development of a business plan, to maximise potential savings.
