April 2024

In New Zealand, where farming practices are integral to the economy and food production, soil fertility plays a pivotal role in determining the success of agricultural endeavours. However, amidst economic challenges such as recession and inflation, ensuring optimal soil health becomes even more imperative for farmers striving to maintain productivity and profitability. Phosphate, a key component of soil fertility, serves as a vital nutrient for plant growth and development. Its presence in the soil is essential for facilitating various biochemical processes necessary for crop production and pasture growth. Through soil testing and fertiliser recommendations, experts like Dr Rajendram help farmers assess and address deficiencies in phosphate levels, ensuring that their land remains fertile and productive. “Phosphate, the silent hero beneath our feet, holds the key to unlocking the potential of our soil. In a world of economic uncertainties, its role in maintaining soil fertility becomes paramount. By nurturing this vital nutrient, we not only cultivate bountiful harvests but also sow the seeds of sustainability for generations to come.” – Dr. Gordon Rajendram By maintaining adequate phosphate levels in the soil, farmers can optimise nutrient uptake by crops and pastures, leading to improved yields and enhanced animal nutrition. Pasture testing and feed analysis further aid in fine-tuning nutrient management strategies, ensuring that livestock receive balanced diets essential for growth and performance. Moreover, prioritising soil health and nutrient management not only benefits farm profitability but also contributes to environmental sustainability. By minimising the use of excess fertilisers and adopting precision farming practices, farmers can reduce their environmental footprint and mitigate the risk of nutrient runoff into waterways. Dr. Gordon Rajendram’s expertise in soil science and agricultural practices underscores the importance of proactive soil management in optimising farm productivity and sustainability. Through ongoing research and education initiatives, he continues to empower farmers with the knowledge and tools needed to safeguard soil health and enhance agricultural resilience in the face of evolving challenges. In conclusion, phosphate stands as a cornerstone of soil fertility, supporting vibrant farming ecosystems and ensuring food security for future generations. By heeding the insights of leading soil scientists like Dr Rajendram and prioritising soil health in farming practices, New Zealand farmers can navigate economic fluctuations while fostering a more sustainable and prosperous agricultural landscape. Contact Dr. Gordon Rajendram Soil Scientist Soil Fertility, Agronomy & Farm Environmental Consultant 021 466077 rajendram@xtra.co.nz www.gordonrajendramsoilscientist.co.nz ‘Bringing science to the farm ‘ Contact Media PA 027 458 7724 phillip@mediapa.co.nz www.mediapa.co.nz

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 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

Nutrient leaching from soil is a significant concern for farmers and environmentalists alike, as it represents both a loss of valuable fertilisers and a potential source of environmental pollution. Dr Gordon Rajendram has provided critical insights into this issue, demonstrating that the amount of nutrients lost via subsurface flow is closely related to the amount of rainfall and drainage. In areas where rainfall and drainage range from 500 to 7000 mm per year, particularly from April to October, nutrients can be washed beyond the root zone, where plants are unable to utilise them. This process is especially problematic for anions like nitrates (NO3-) which are highly mobile and tend to leach easily. Anions also carry cations with them, such as calcium (Ca2+), exacerbating the loss of nutrients. For instance, Dr Rajendram’s research indicates that sulphur leaching can be between 40 to 70 kg/ha/year, costing approximately $28 to $49 per hectare annually. When it comes to nitrogen (N), a critical element for plant growth, the figures are even more striking. Without any nitrogen applied, between 21 to 26 kg/ha/year can leach, amounting to around $43 per hectare each year. However, when 200 kg of nitrogen per hectare is applied, the leached amount can increase to about 60 kg/ha/year, with the cost rising to around $125 per hectare annually. And with a higher application rate of 400N, up to 100 kg N/ha/year may leach, costing approximately $209 per hectare each year. Calcium leaching, which equates to the loss of half a ton of lime, is around 150 kg Ca/ha/year, resulting in a cost of about $13 per hectare per year. Other nutrients like magnesium (Mg), sodium (Na), and potassium (K) also experience significant leaching, with costs of $30, $50, and $19 per hectare per year, respectively, for losses of 30 kg Mg, 50 kg Na, and 10 kg K. Dr Rajendram asserts that to mitigate nutrient leaching, farmers need to employ strategic fertiliser management. This includes soil testing to determine the existing nutrient levels, timing fertiliser applications to match plant needs, and using technologies such as controlled-release fertilisers, nitrification inhibitors and management practices such as using standoff pads/herd homes “Effective nutrient management is key to both economic efficiency and environmental stewardship,” Dr Rajendram advises. “By optimising fertiliser use, we can reduce leaching losses, saving both our resources and our rivers.” This holistic approach to agriculture is essential for sustainable farming practices that protect both the productivity of the land and the health of the environment. 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 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