Optimising crop nutrition will be vital this spring after the wet winter, says Agrovista
Optimising crop nutrition will be vital this spring after the wet winter, says Agrovista and Norfolk-based agronomist, Craig Green.
Many autumn-sown crops have looked pale and stressed over the past few weeks after one of the UK’s wettest winters left them short of key nutrients.
Spring crops are also at risk unless following a cover crop, says Craig.
Micronutrients such as manganese, magnesium, copper, zinc and sulphur are likely to remain in short supply over the next few weeks, and nitrogen levels may also be lower than expected, he adds.
“Prolonged rainfall will have moved these nutrients down the profile, often beyond the reach of roots. To make matters worse, stressed crops have smaller root volumes,” says Craig.
To help alleviate or prevent stress, he recommends Terra-Sorb, an amino-acid based biostimulant plus trace elements that helps boost nutrient uptake, photosynthetic activity and root and shoot growth.
“It can be used in any situation to increase vigour and plant development in spring – I describe it as Red Bull for crops,” says Craig.
“It is compatible with fungicides so in winter cereals we tend to use it at the end of tillering at 1.5-2.0 litres/ha, mixed with the T0 spray, so plants are in good shape before entering stem extension.”
However, it is spring crops, particularly sugar beet and maize, where he recommends it most frequently.
“Two years of trials in the UK have shown significant potential to increase yield and sugar content in beet, especially on lighter soils and sands that are prone to drought,” he notes.
“It is best applied when the crop has 2-4 leaves at 0.3-litres/ha, tank-mixed with a post-emergence herbicide. Plants are more vigorous and put down bigger roots and are better able to grow away and withstand stress.”
Independent (CMi) trials have shown 2-litres/ha of Terrasorb increased sugar content by 0.43 per cent at the four-leaf stage, and yield by 1.42t/ha, says Craig.
Use on maize
He also uses it on maize crops for biogas to promote root and cob development. “Cool May temperatures can slow growth and cause yellowing as roots struggle to develop and access nutrients, particularly phosphate. This is particularly the case with maize grown in arable rotations that haven’t received FYM,” he explains.
“Terra-Sorb can also be used with fungicides, so can be applied later on to provide the crop with extra energy three to four weeks ahead of tasseling to extend the cobbing period.”
Nitrogen is also likely to be at sub-optimal levels in many fields. Wet weather after early N applications won’t have helped efforts to restore soils depleted by the winter deluge, says Craig.
Maintaining sufficient accessible N through the growing season is necessary for optimum performance. “Most nitrogen is generally applied to winter crops in the early stages of crop development – for example, about 75 per cent goes onto wheat by GS 32. Spring crops such as maize often receive all of it in the seedbed.
“We need to ensure there is enough for plants to make optimum use of it when they start building yield,” he notes. “Crops on light soils prone to leaching, soils prone to waterlogging, or cold soils when N is applied early are at risk.”
In these cases, Craig recommends N-Lock, a nitrogen stabiliser that slows the bacterial conversion of ammonium (bagged N) to leachable nitrate for up to six weeks.
Winter wheats, particularly second and bread-making wheats, as well as feed barley, are likely to give reliable benefits where nitrogen is the key limiting factor for yield.
“Agrovista grower trials have shown a 0.7t/ha increase when targeted at situations likely to give the best responses, a 4:1 return on investment,” Craig notes.
High yielding maize varieties also produce good responses as they are prone to running short of N during cob fill, he explains (see Farmers Guide p101, March 2016).
Whatever the crop, N-Lock should be applied near the time of maximum N application, says Craig. “In winter wheat, for example, it can be tank-mixed with the T1 fungicide, while in maize it can be applied straight after drilling with the pre-emergence herbicide.
“The only proviso is that the N-Lock needs to be incorporated into the soil or needs 12mm of rain within 10 days of application, so that should be borne in mind.”
Growers are being extra cautious this season on inputs, and products like these may be first in line to be dropped, says Craig. “But growers have already made the biggest investment by planting the crop. I’d argue that investment needs protecting – yield is king, especially when prices are under pressure.”
*Craig Green is an agronomist with Agrovista, based at Great Ellingham, Norfolk ([email protected]).