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Legume pastures boost nitrogen

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Released on:
Monday, 10. September 2018 - 14:30

Department of Primary Industries and Regional Development (DPIRD) research and development into pastures and livestock was shared with producers at a recent pasture and livestock update in Moora, hosted by Meat and Livestock Australia (MLA).

DPIRD senior research officer Angelo Loi said trials conducted by the department and Murdoch University had shown that a single year of legume pasture could provide sufficient nitrogen for subsequent crops for at least two, potentially three, years.

“Provided legumes are nodulated and soil fertility adequate, an impressive amount of nitrogen can be generated for the following crop,” Dr Loi said.

“For every tonne of legume pasture dry matter, such as serradella, biserrula, bladder clover, or medics, the equivalent of 20kg or urea is produced and available for the following crop.

“Field trials that compared crops grown after a legume pasture rotation, with and without added nitrogen, showed no significant difference in yield, indicating crops are able to obtain sufficient nitrogen from the soil nitrogen pool.

“Some trials revealed that adding nitrogen to the following crop made no significant difference, even after three years, demonstrating the application of nitrogen is sometimes unnecessary.”

To calculate how much nitrogen had been fixed from legumes, it was important to know how much legume biomass had been produced. Exclusion cages could be used to get accurate results for grazed legumes.

Dr Loi also discussed weed control in the annual pasture legume serradella, which produces large quantities of high-quality fodder with high seed yields on deep, course textured soils where it is well adapted.

“Serradella is a very acid-tolerant species and is generally adapted to a range of soil textures, provided soil pH is below 7.5,” Dr Loi said.

“Broadstrike®, Spinnaker® and Raptor® are registered herbicides for broadleaf weed control in serradella, and grass weeds can usually be controlled with a selective grass herbicide.”

Imidazolinone herbicides could be used after sowing before rainfall, and before the serradella germinates, to take out broadleaf weeds such as radish, capeweed, and double gees. Imidazolinone-tolerant varieties of barley or wheat could be grown successfully with serradella as a forage mix.

DPIRD livestock researcher John Paul Collins discussed technology available to livestock producers to increase labour efficiency and make improved business decisions, with a focus on the use of electronic identification (EID) for animals.

“Producer case studies undertaken by the department on EID for individual animal management indicated that using EIDs made data collection for sheep production more accurate, easier, faster and more likely to happen,” Mr Collins said.

“Investment into electronic identification showed that for every $1 invested, there was generally a $5 to $10 return in production improvement and labour savings.

“The highest returns generated were for new product applicators that allowed drench, backline or vaccine to be individually dosed, based on body weight and the treatment recorded against the EID.

“The case studies on sheep handlers showed the technologies tested have other benefits, such as reduced operator fatigue, better efficiency and easier collection of data.”

Department staff will also contribute to other pasture and livestock updates throughout the grainbelt.

Angelo Loi
DPIRD senior research officer Angelo Loi highlighted research by DPIRD and Murdoch University which had shown that a single year of legume pasture could provide sufficient nitrogen for subsequent crops for at least two, potentially three, years.

John Paul Collins, oolorama, March 2018
DPIRD research officer John Paul Collins highlighted technologies tested by the department and producers with the aim of saving time and money for livestock producers.

Media contact: Jodie Thomson/Dionne Tindale, media liaison  +61 (0)8 9368 3937