An investigation into the reinforcement of existing permanent pastures to increase pasture quality and extend the grazing season

by HJF Grobler (corresponding author), manieg@elsenburg.com; CSS Lamberts, clydel@elsenburg.com; and R Julies, ronwynj@elsenburg.com

Introduction

Developing livestock farmers in the Southern Cape farm mainly on small land units. These areas, often characterised as “old fields”, which were formerly used for grain or vegetable cultivation, are often marginal with respect to soil and/ or are degraded and function as rain-fed systems. The pastures on these areas consist primarily of volunteer species like the subtropical grasses “taaipol” (Sporobolus africanus/Eragrostis plana), kikuyu (Pennisetum clandestinum), couch grass ( Cynodon dactylon ), and some annual legumes. The major challenges in these systems are low forage quality and pasture availability from late autumn to early spring. An investigation was undertaken in 2018 to determine whether pastures could be reinforced using low-risk and low-cost methods to improve forage quality and extend the grazing season without removing the existing pasture.

Methodology

The investigation methodology was based on pasture reinforcement practices developed by Australian farmers. The goal was to reinforce existing pasture, minimise till, and preserve soil cover and living roots on the land as long as possible (Jones, 2011; Soils for life, 2012). The methodology adapted for this investigation involved the planting of a mixture of pasture species into existing pasture in autumn (March to April). The following principles were applied during the process of pasture renovation:

• Competition of the existing pasture was reduced during germination by the application of a contact herbicide (Paraquat at 0,5 to 1 ℓ/ha).

• Soil disturbance was kept to a minimum by observing conservation agriculture principles.

• A pasture mix was established, which consisted of legumes, grass, and forbs (annual and/or perennial) to advance soil biology with appropriate fertilisation.

• Planted areas were strategically rested for grazing, hay, and/or seed set.

With the above principles in mind, the system was assessed over three seasons with a prototype planter (Figure 1) equipped with:

• a disc to cut open the existing sward at a 30 cm spacing;

• a tine to loosen the soil and eliminate compaction;

• separate bins for the fertiliser, small seed and larger seed to allow for precision application; and an occasional rest be investigated. Close observation of the effect of cropping on perennial pasture biomass is necessary to determine the frequency of rest in a specific location.

• press wheels to ensure good seed-soil contact.

Results and discussion

Observations demonstrated that species planted in existing summer pastures established and produced satisfactorily, ensuring leafy, quality pastures for lactating ewes. Summer pastures recovered well for stock grazing.

With these possible benefits observed, an implement manufacturer (Piket Implements) was approached to design and manufacture a robust planter, complying with the above specifications and able to operate in uncultivated fields at larger operations. The first manufactured planter was obtained and tested at a developing project in Bitou (Figures 2 and 3). A temperate grass and legume mixture was planted into a kikuyu-based pasture in May 2021.

Continuous establishment of annuals into existing perennials have in some instances reduced perennial biomass over time, as recorded by Millar and Badgery (2009), during Australian pasture cropping trials. It is therefore recommended that

Extension implications

The practices developed during this project have been well received by individual farmers and at farmer information sessions so far. Practical demonstrations to producers will continue, with roll-out of the practices to projects commencing in the autumn of 2021.

References

JONES, C. 2011. Carbon that counts www.amazingcarbon.com.

MILLAR, G.D. & BADGERY, B. 2009. Pasture cropping: a new approach to integrate crop and livestock farming systems. Animal Production Science, 49:777-787.

SOILS FOR LIFE, 2012. Innovations for Regenerative Landscape Management: Case studies of regenerative land management in practice. www.soilsforlive.org.au.

Key words: pasture, regenerative, conservation, developing farmers, minimum till