Article taken from Farmers Guide online
Obtaining good returns from livestock is all about providing a good feed at key stages of their production cycles. Forage maize offers an excellent food source with high starch levels and energy characteristics and high dry matter yield potential. And optimising yield from that crop can be helped by using the nitrogen stabiliser N-Lock, says Dow AgroSciences. It says that N-Lock can deliver “significant"" benefits by protecting fertiliser inputs until the crop really needs it later in its lifecycle. Location, good seedbed preparation, soil pH and appropriate variety choice are all key factors to consider when growing forage maize. Crop nutrition also plays a vital role —in particular nitrogen application, the company states. Since most, if not all, nitrogen is applied at the establishment/early stages of the crop, often there isn't enough nitrogen left for the latter stages of crop development, to the extent that yield potential is often limited, especially with modern potentially higher-yielding varieties. When nitrogen fertilisers are applied to soil, a nitrification process takes place whereby the ammonium nitrogen is converted to nitrite by nitrosomonas bacteria, and then to nitrate by the bacteria nitrobacter.
Ammonium is positively charged and is attracted to the negatively-charged soil particles, so it can't be leached from the soil rooting zone after heavy rain. However, nitrite and nitrate are negatively charged and are therefore repelled by the soil particles. Hence, in these forms, nitrogen can be leached through the soil profile. In wet conditions it can also denitrify and be lost to the atmosphere as greenhouse gases. Keeping nitrogen in the ammonium form enables the nitrogen to be attracted to the soil particles and remain in the rooting zone, Dow concludes. Its N-Lock works by inhibiting the nitrosomonas bacteria. This effectively stabilises the nitrogen and helps to optimise yield and quality potential — with the additional bonus of environmental benefits. Last season Agrovista ran a trial to show the performance of 56 forage maize varieties, and the benefits of using N-Lock. The site, at Great Ellingham in Norfolk, is a sandy clay loam soil —medium but bordering on the lighter section. The land was prepared and fresh cattle farmyard manure applied at 8t/ ha was ploughed in with the cover crop. Nitrogen was applied at 40kg/ha as a seedbed fertiliser followed by 20kg/ ha of nitrogen and sulphur with post-emergence herbicide. A Sumo cultivator was used immediately prior to drilling to loosen the soil and create a seedbed. The maize was drilled on 10th April in dry and warm conditions, with the drill calibrated to 38,000 seeds/ha —10 rows per variety.The crop was drilled at right angles to plot length, and treatments were overlaid to avoid a tramline effect. Two days later N-Lock was applied to a 12m strip at the full rate.This was separate from a pendimethalin and Agrovista Remix adjuvant spray on the same day, although in practice all three products can be applied as a tank mix. The site wasn't rolled. N-Lock needs to be incorporated into the soil within 10 days of application, either by light cultivation or with 12mm of rain. In the trial, 14mm fell the day after application, which was ""ideal"", says Dow.
The trial followed a crop of rye and therefore received a ""robust"" post-emergence treatment at the crop's 4-true leaf stage. The crop was then left and monitored. In the N-Lock-treated crop there was no real visual difference in the crop up to the fifth leaf, although the fifth leaf did appear to be thicker and wider on the treated side. However, in the N-Lock-treated crops the later varieties had bigger cobs with more grains pollinated. In the early varieties cob sizes were similar, but the spindle was visibly bigger with more grains round the cob. Agrovista agronomist Craig Green says: ""I was pleased with N-Lock's performance. I'd always viewed it as somewhat muck and mystery, but Dow AgroSciences has got it right. ""When used on nitrogen-limiting soils it works well. It certainly seems to prolong the availability of what little nitrogen there might be in the soil, and it seems to have benefits in the maize. ""Average cob weight in the N-Lock-treated varieties was consistently higher than that of the untreated ones, and showed a marked increase in Ramirez, Kougar, Dualto, Hobbit and Absalonf.""