December 2024

Summer brings sunshine, barbecues, and beach days – but for farmers and gardeners, it also brings a host of soil-related headaches. Dr Gordon Rajendram, an agricultural expert with a flair for solving soil dilemmas, explains the seven most common summer soil problems and how to tackle them with a bit of wit and wisdom. 1. Soil CompactionThe summer heat can turn soil into something resembling concrete. Over-grazing or heavy machinery exacerbates this issue. Introducing deep-rooted cover crops like lucerne can break up compacted layers naturally. Research shows that soil aeration through biological methods, such as deep-rooted plants improves soil structure and water infiltration, which is critical in avoiding compaction during the dry summer months. 2. WaterloggingSummer storms can saturate the soil, reducing oxygen availability to roots. The article by Cameron et al. (2007) highlights that waterlogged soils increase denitrification losses, harming soil nitrogen balance. Installing mole drains or creating raised beds can prevent prolonged waterlogging and protect crops from stress. 3. SalinityExcessive irrigation and high evaporation rates can cause salts to accumulate, damaging plants. Saline soils reduce the availability of water to crops. Flushing salts with good-quality water or growing salt-tolerant crops like barley can mitigate salinity until soil conditions improve. 4. Nutrient LeachingSummer rains can wash away essential nutrients like nitrogen, a major concern highlighted in Cameron et al.’s research. Nitrate leaching not only depletes soil fertility but also contributes to groundwater contamination. Using slow-release fertilisers or applying nitrogen in smaller, frequent doses can minimise leaching. Incorporating cover crops or organic matter also improves nitrogen retention. 5. CrustingSoil crusting occurs when rain compacts surface soil, reducing water infiltration and seedling emergence. A fine layer of mulch can protect the soil and keep it cooler, enhancing germination success rates. 6. WeedsWeeds thrive in disturbed or nutrient-rich soils, often outcompeting crops for water and nutrients. Maintaining healthy soil structure and promptly removing weeds before they seed are vital. 7. Heat StressHeatwaves dry out soil, leading to reduced microbial activity and moisture levels. According to Cameron et al., maintaining soil organic matter is key to improving water retention and providing a buffer against temperature extremes. Shade cloths, mulch, and regular irrigation can keep the soil and plants cooler. “Summer soil challenges might seem overwhelming, but with the right strategies, they can be managed effectively,” says Dr Gordon Rajendram. Dr Rajendram’s solutions combine practical advice with a touch of humour, ensuring farmers and gardeners can enjoy their summer with healthy, thriving soil. By addressing these common issues with actionable steps, he proves that even under the blazing summer sun, soil problems don’t have to stick. Cited Source: Cameron, K. C., Di, H. J., & Moir, J. L. (2007). Nitrogen losses from the soil/plant system: A review. New Zealand Journal of Agricultural Research, 50(2), 349-359. For more information, please contact: Contact Dr Gordon Rajendram 021 466077 rajendram@xtra.co.nz www.gordonrajendramsoilscientist.co.nz Contact Media PA phillip@mediapa.co.nz 027 458 7724 www.mediapa.co.nz

Summer heat can significantly impact soil health by disrupting the balance of soil microbes. These tiny organisms are essential for nutrient cycling, soil structure, and crop productivity. Dr Gordon Rajendram, a soil health expert, says, “Understanding how summer temperatures affect microbial populations is key to maintaining healthy soil and good yields.” Warmer temperatures can initially boost microbial activity, as beneficial microbes thrive in heat. However, this can lead to faster depletion of organic matter, reducing long-term fertility. If the heat becomes extreme, the microbial community may shift, with harmful pathogens outcompeting beneficial microbes. A study in Nature Microbiology highlights that rising temperatures not only influence microbial abundance but also alter the composition of soil microbial communities, which can lead to imbalances that harm soil health (Zhang et al., 2023). Dry conditions in summer present further challenges. Moisture is critical for microbial life, and dry soils can stress or even kill microbes reliant on water. According to Microbiometer, a lack of soil moisture can shrink microbial populations and reduce their diversity, hindering vital processes like nitrogen fixation and organic matter decomposition. This often results in poorer soil quality, reduced crop yields, and increased reliance on fertilisers. Farmers can take practical steps to protect their soil microbes: “Fostering soil biodiversity is one of the best defences against the challenges of rising temperatures,” says Dr Rajendram. By adopting these sustainable practices as well as soil and pasture testing, farmers can protect their soil microbes, sustain crop productivity, and promote resilience for the future. References: For more information, please contact: Contact Dr Gordon Rajendram 021 466077 rajendram@xtra.co.nz www.gordonrajendramsoilscientist.co.nz Contact Media PA phillip@mediapa.co.nz 027 458 7724 www.mediapa.co.nz