Rural

Soil structure plays a pivotal role in determining the agricultural productivity and sustainability of New Zealand’s diverse landscapes. Dr. Gordon Rajendram, a leading soil scientist, examines how the structural integrity of soil affects everything from water retention and drainage to root development and nutrient uptake. Understanding these differences is crucial for effective farm management and long-term soil health.

In New Zealand, soil structure varies significantly not only between the volcanic soils in regions such as Waikato and Taranaki, and the sedimentary soils found predominantly in areas like Canterbury but also across other soil types such as peaty soils in wetter regions and clay soils in drier areas. Volcanic soils benefit from a loose, porous structure due to the presence of allophane, a mineral that not only enhances soil stability but also aids in significant carbon storage, with carbon levels reaching 10-12%, thereby enriching the soil’s organic content. This structure promotes excellent water retention and nutrient availability, making these soils ideal for high-demand agricultural activities, such as dairy farming.

Conversely, sedimentary soils present different challenges. Dr. Rajendram explains, “Sedimentary soils tend to be denser and can suffer from compaction more easily, which reduces aeration and negatively impacts root penetration and moisture permeability.” These soils typically have lower organic matter content, generally around 3-5% carbon, making them more prone to degradation. which can lead to faster degradation and fertility loss over time if not managed correctly.

Peaty soils, while excellent for specific horticultural uses due to their high organic matter content, require careful water management to prevent over-saturation, which can suffocate plant roots. Similarly, clay soils, known for their ability to retain water, are advantageous in drier regions but can become hard and crack when dry, posing challenges for root growth and soil aeration.

Effective management practices are essential for maintaining the health of all these soil types. Dr. Rajendram highlights that strategies such as regular soil testing, appropriate crop rotation, and the careful application of organic amendments are vital. For volcanic soils, maintaining the structural integrity involves minimal tilling and controlled grazing to prevent compaction. For sedimentary soils, improving structure may involve more frequent organic matter addition and careful water management to avoid surface crusting and compaction.

Dr. Rajendram emphasises that by tailoring farming practices to the specific type of soil structure, New Zealand farmers can enhance productivity and ensure the sustainability of their valuable agricultural lands.

 Contact Dr Gordon Rajendram

021 466077

rajendram@xtra.co.nz

www.gordonrajendramsoilscientist.co.nz

Contact Phillip Quay

phillip@mediapa.co.nz

027 458 7724

www.mediapa.co.nz

In the diverse agricultural landscape of New Zealand’s North Island, understanding and enhancing soil structure is crucial for farming success. Profile Fertilisers stands at the forefront of providing tailored soil solutions that cater to the unique characteristics of the region’s varied soil types, from volcanic soils in areas like Waikato and Taranaki to the granular and pumice soils of the Central Plateau and the Northland region.

Volcanic soils, known for their rich allophane content, offer excellent water retention and nutrient availability, which are advantageous for farming. However, these soils also require careful management to prevent compaction and maintain their organic content. Profile Fertilisers supports these efforts with bespoke fertiliser blends that maintain the delicate nutrient balance essential for preserving the structural benefits of allophane-enhanced soils.

In addition to volcanic soils, the North Island features granular soils and pumice soils, which present their own set of challenges and benefits. Granular soils, often found in Northland, require careful nutrient management to avoid leaching due to their typically coarse texture. Pumice soils, whilst well-drained and light, can be nutrient-poor and prone to erosion. Profile Fertilisers addresses these issues with specially formulated products that improve nutrient retention and soil stability, enhancing plant growth and soil health.

Profile Fertilisers advocates for practices such as minimal tilling and controlled grazing to protect soil structure across these varied types. Their slow-release fertilisers encourage deep root development, crucial for maintaining soil porosity and aeration. This approach not only helps in preventing compaction but also optimises the absorption of nutrients, reducing the risk of runoff and environmental impact.

For farmers in New Zealand’s North Island, adapting fertilisation strategies to the specific needs of their soil type is key. Profile Fertilisers provides not only the necessary nutrients but also expert advice and support to ensure that soil management practices lead to sustainable productivity and long-term success. Through strategic partnerships with Profile Fertilisers, New Zealand farmers can enhance the health and productivity of their diverse soil types, securing the sustainability of their agricultural ventures.

Contact Profile Fertilisers

Don Henderson: 021 643 698

donh@profilefert.co.nz

www.profilefert.co.nz

Contact Phillip Quay

phillip@mediapa.co.nz

027 458 7724

www.mediapa.co.nz

Agraforum New Zealand, a key player in agricultural consultancy, focuses on the varied landscapes of New Zealand’s South Island, which present unique challenges and opportunities for soil management. The region’s predominant sedimentary soils, derived from greywacke and other sedimentary rocks, are distinct from the volcanic soils found in the North Island. These sedimentary soils, especially prevalent in areas like Canterbury, play a central role in the island’s dairy farming operations.

These soils in the South Island typically feature lower organic matter levels, with carbon content generally ranging between 3-5%. Agraforum New Zealand recognises the susceptibility of these soils to degradation, particularly due to their finer and less robust structure. “The structural challenges of sedimentary soils make them prone to compaction, significantly impacting their fertility and the productivity of our farms,” notes Dr Gordon Rajendram, a leading soil science expert working alongside Agraforum NZ.

The intensive agricultural practices common across the South Island, including continuous dairy farming and cropping, often exacerbate soil degradation. The frequent use of chemical fertilisers, such as Diammonium Phosphate (DAP) and ammonium sulphate, leads to soil acidification, which in turn diminishes soil quality. “Such practices disrupt the microbial life within the soil, which is vital for sustaining soil health and fertility,” explains Dr Rajendram.

Despite these challenges, the South Island’s diverse soil types, including loess in some regions, offer significant agricultural potential beyond traditional dairy farming. These fine, wind-blown silt particles are particularly well-suited for viticulture and certain types of horticulture, industries where the South Island has carved a niche.

One of Agraforum NZ’s testing locations

Committed to promoting sustainable soil management practices, Agraforum New Zealand advocates strategies such as crop rotation, reduced tillage, and the strategic use of soil tests and analysis to maintain or improve soil health. By adopting these sustainable practices, Agraforum aims to ensure the longevity and productivity of the agricultural lands, preserving the unique soil landscape of New Zealand’s South Island for future generations.

Contact Agraforum NZ

Mobile: 0274 485 159
Email: allan@agraforum.co.nz

www.agraforum.co.nz

Contact Phillip Quay
phillip@mediapa.co.nz
P: 0274 587 724
www.mediapa.co.nz

In the verdant landscapes of New Zealand, where agriculture forms the backbone of the economy, maintaining the right balance of nutrients in the soil is critical for both crop yield and environmental sustainability. Dr Gordon Rajendram, a renowned soil scientist, draws attention to an often-overlooked issue: the signs of excessive phosphate levels in the soil, a condition that can have far-reaching consequences for both agriculture and natural ecosystems.

Phosphate is an essential nutrient for plant growth, but like anything in excess, it can lead to problematic outcomes. One of the primary signs of too much phosphate in the soil is the inhibition of plant uptake of other necessary minerals, such as iron, zinc, and manganese. This nutrient imbalance can result in poor plant health and reduced growth, a paradoxical situation where more is indeed less.

Moreover, excessive phosphate can lead to algal blooms in nearby water bodies, as runoff carries the surplus nutrients into rivers and lakes. These blooms not only disrupt aquatic ecosystems but can also pose a risk to animal and human health. In New Zealand, with its extensive coastlines and waterways, this issue is of particular concern, highlighting the need for careful nutrient management.

Dr Rajendram points out that soil testing is a crucial step in identifying excessive phosphate levels. Such tests can help farmers and land managers make informed decisions about fertiliser application, reducing unnecessary inputs and mitigating environmental impacts.

Another sign of too much phosphate is the appearance of certain weed species that thrive in high-phosphate conditions. These weeds can outcompete crops and native plants, further disrupting agricultural productivity and biodiversity.

Phosphate holds a pivotal role in the tapestry of soil nutrients, serving as a cornerstone for plant growth and agricultural productivity. Dr Gordon Rajendram emphasises the significance of phosphate, noting, “Phosphate is akin to a key that unlocks the energy potential within plants. It’s essential for photosynthesis, energy transfer, and the synthesis of nucleic acids and cell membranes. Without adequate phosphate, plants cannot thrive or produce at their full potential.”

In conclusion, recognising and addressing the signs of excessive phosphate in New Zealand’s soils is a critical step towards sustainable agriculture and environmental stewardship. Through careful management and a commitment to balance, the country can continue to thrive both economically and ecologically.

Contact Dr Gordon Rajendram

021 466077

rajendram@xtra.co.nz

www.gordonrajendramsoilscientist.co.nz

Contact Phillip Quay

phillip@mediapa.co.nz

027 458 7724

www.mediapa.co.nz