Animal impact or fire for pasture regeneration?

The second of a three soil health webinars was held today and heard from Dukes Plain in the Brigalow belt and Winona in the NSW central highlands. Both spoke about how they have improved soil health, and in the process increased yield and reduced costs. A feature of the soil health webinars is that some farmers are now aiming for 100% groundcover. You can read these and other case studies here.

A third case study attracted my attention. It said:

‘In areas that aren’t grazed, pastures go to seed and senesce, by which time they are of little use for fattening cattle…. There are only two ways to ensure that grasses remain useful for grazing: animal impact or burning.

Leuceana: Friend or Foe?

Leuceana rows on pastures

Leuceana (Leuceana leucocephala subspecies glabrata) is described as a high protein, highly palatable and productive forage legume that can put weight on cattle like no other forage plant. Its ability to fix nitrogen improves grass quality and quantity, encourages water infiltration and reduces erosion.

However, in Queensland, heavy seed production in ungrazed areas can allow it to spread and become an environmental weed.

Commercial cultivars are a different subspecies to Coffee Bush found around Darwin (subsp. leucocephala), which is not productive or used for grazing.

Chris Muldoon, who farms with his family in the Douglas Daly, is not sure whether subspecies glabrata will spread in the NT.

“We planted rows of Leuceana four years ago with a 20m buffer to the boundary. It hasn’t moved between the rows or towards the boundary.”

“It definitely needs to be managed, there’s no doubt about that. We are part of the Leuceana network based in Qld that has developed a code of practice to minimise the risk of spread.”

Degradable plastic mulch

David McGrath from EconVerte at the NT Farmers Field Day at Red Dirt Melons, Katherine

Top End melon growers would like to use degradable plastic beneath crops instead of the conventional plastic, but as yet, no product has been found suitable for the Top End’s climate.

Plastic mulch is used on row crops to reduce pests, weeds and retain water, soil and nutrients. Stuart Smith from DPI&F estimated that 7,000km of conventional, non-biodegradable plastic mulch was rolled out in the NT in 2012. This is normally burnt or buried each year.

Degradable and bio-degradable plastics are available but expensive and tend to break down too quickly in the Top End, rendering them useless.

David McGrath, founder of EconVerte, is trying to address the gap in technology with a product called Degricover, a degradable plastic mulch film. Degricover has a retarding agent and degradant. The retarding agent keeps the plastic strong so it isn’t split by rocks or birds. The depletion time of the retarding agent is pre-determined to 3, 6, 8 or 10 months. Then the degradant is exposed and the product starts to become brittle and breaks up.

Rotational grazing in central Australia

Mt Riddock Station

I visited Steve Cadzow with CLMA’s Camilla Osborn in November 2012 to discuss innovative practices in central Australia. Steve talked about rotational grazing, which he does on 2% of Mt Riddock Station. It was interesting to hear how it can improve groundcover.

‘When we started rotational grazing the buffel tussocks weren’t touching. Now it’s nearly a carpet and it responds quickly to rainfall. It’s unreal. It’s gone from struggling with 50 head to having 1100 steers through it.

‘We’ve got eight paddocks, four are about 1000ha (10km²) each and the other four range from 400-800ha. There is a central water point for both sets of four with a trap in and trap out, so when we move them after 3-4 weeks we close one out-trap and open another. The cattle only move about 2.5km from water and in one trial paddock there are areas they don’t get too because it’s too far away.

Land Condition

Land condition is the capacity of the land to respond to rain and produce useful forage. It is a measure of how well the grazing ecosystem is functioning. For example, is the soil absorbing and storing rain or is it like a table top with water exiting quickly and causing erosion? Is the pasture palatable, perennial, and capturing maximum solar energy and responding quickly to minor rain, or is it struggling?

Land condition is related to stability, or the ability of the land to keep functioning effectively following disturbance (e.g. drought, fire, overgrazing). Land can be classified into A, B, C, or D condition to indicate function and stability. Knowing the condition of the land can inform management decisions so that condition does not deteriorate or is improved.

The video above introduces the concept of land condition. Guides are available for the Barkly, Sturt Plateau and Victoria River Districts, or visit the Future Beef website

Acknowledgement: Grazing Land Management - Katherine version - workshop notes - MLA Edge network

Darryl Hill's soil sense at Mt Bundy Station

Darryl Hill holds the attention of attendees at the Mt Bundy Field Day

Darryl Hill has spent years observing erosion on pastoral stations and testing erosion controls first hand. He is now recognised as one of the leading experts in erosion control across Australian Rangelands.

Darryl presented a soil conservation workshop at the Mt Bundy Station Field Day recently. These are what I thought were his key messages:

·         The greatest cause of fenceline or track erosion is windrows channelling water flow away from natural drainage lines - Reinstate the natural flow direction as often as possible (by removing windrows or installing banks).

Emerging weeds in the Top End



Yellow Oleander (NT Dept. Land Resource Management)

 

The field day at Mt Bundy raised a few interesting and emerging weed concerns. Fergal O’Gara has noticed that Yellow Oleander is suddenly appearing in paddocks. This tree which grows to 10m is a declared weed in Qld and all parts are poisonous to stock and humans if ingested. Fergal also highlighted concern with Neem, a bird dispersed tree with leaves unpalatable to stock.

Scott Witham said Lantana, a Weed of National Significance, appeared more vigorous on his property this year. Lantana is toxic and allelopathic, meaning it releases chemicals into the soil which prevent germination from some other plants. It can alter fire regimes and impact grazing though stock toxicity and loss of productivity.

Soil Health at the Mt Bundy Field Day with Fiona McBean

Fiona McBean is based at Camp Creek Station in the Top End and previously spent years working at her father’s Douglas Daly property Bonalbo. Dissatisfied with pouring money into animals and the ongoing fight with weeds, she decided to challenge the system. She began by studying soil health and identified three key components that need to be understood and addressed:

·         Chemical balance

·         Structural stability

·         Biological activity

Nutrients are made accessible to plant life (re-cycled) thanks to organisms living in the soil. Fiona believes that a healthy and balanced community of these organisms, and chemicals like magnesium and calcium, can provide all your nutrient requirements.

“Getting the balance right is very hard, especially on sandy soils, but by no means impossible.”

Six characteristics of healthy soils

A healthy soil is one that is productive, easy to manage for the intended land use, and has properties that promote plant, animal and human health while maintaining environmental quality.

The Soil Health Knowledge Bank highlights six characteristics of healthy soils:

1.   The level of soil organic matter is maintained

The amount of organic matter in a soil is an indicator of the potential sustainability of a system. The optimal level of soil organic matter for any given soil is one which supports the capacity of the soil to hold and supply water and nutrients to plants, provides energy for soil fauna, improves crop/biomass yields, and moderates net greenhouse gas emissions.

Ten habits of healthy soil farmers

1. Maintain organic matter and ground cover

High organic matter returns will increase the potential for building soil organic matter.

Manage grazing (stocking rates; grazing interval) to maintain ground cover

Use minimum-till methods of sowing and minimise soil disturbance

Incorporate rotations and farming systems to support plant diversity

Maintain native vegetation condition to support biodiversity

2. Maintain soil fertility

Consider your soil type, the existing pH and nutrient status, and the form and amount of fertiliser required to suit your farming situation.

Time applications to reduce losses

Manage rotations to assist in maintaining soil fertility - different crop types will use nutrients in different amounts and from different parts of the soil profile.