Biopest control, permaculture, regenerative hydrology & silvohorticulture

This week I focus on some of the talks from the Oxford Real Farming Conference. There was so much to interest me and here are a few highlights.

Jan 15, 2025

🌱 I'm Sally Morgan, an organic gardener and botanist who loves to experiment. Here you can read about matters relating to climate change, sustainability, organic gardening and growing veg, helping you to become a climate savvy gardener.🌱

Enhancing biopest control: the food spray approach

I found this session hosted by Pesticide Action Net (PAN) absolutely fascinating. Farmers around the world use far too many pesticides, and their use continues to increase year by year. Pesticide use is devastating ecosystems and endangering farmers, with alarming statistics like 44% of farmworkers suffering acute pesticide poisoning annually, with more than 255 million poisoning incidents a year in Africa alone.

This is particularly problematic in the Global South, where improper disposal, counterfeit products, and food residue issues are common. In Ethiopia, for example, vegetable growers often apply 10 to 30 rounds of pesticides per year, wiping out beneficial organisms and creating pest resurgence. That’s where the food spray comes in - a groundbreaking idea developed by Robert Mensah in the 1990s while implementing Integrated Pest Management within the Australian Cotton industry.

He found that too few beneficials were active around the cotton plants and he needed more of them to control pests and he also wanted them to move deeper into the crop

Mensah’s spray mimicked the chemical signals plants release when under pest attack, and attracted predatory insects deep into the crop. Made from protein-rich ingredients like brewer’s yeast and fermented maize, it worked effectively over 400 metres.

PAN UK collaborated with Mensah to adapt the spray for African smallholders growing cotton, with trials of the maize-based product taking place in Benin and Ethiopia.

The results were remarkable. By combining the spray with complementary strategies, such as planting refuge crops (e.g. maize around cotton or alfalfa plants around onions) to provide shelter for the beneficials, the farmers saw a 40% increase in yield compared with untreated organic fields, thanks to boosted predator populations. The key was early application to establish predator populations before pests arrived, with pest-to-predator ratios carefully monitored throughout.

This innovative approach is transforming cotton farming in Ethiopia, with organic yields now comparable to conventional ones but at far less cost. The program, taught through Farmer Field Schools, has trained 8,000 farmers across 22 villages, and the regional government is promoting the area as an organic cotton corridor, with the first organically certified cotton being produced in 2017.

Could this idea work for vegetable growers? Veg trials in Ethiopia found yields from crops treated with the food sprays were similar to those which received neem treatments, but not as high as those treated with inorganic pesticides. However, the farmers saw higher net income due to reduced costs. By 2024, more than 1500 farmers had been trained to use the food sprays and refuge barriers on veg crops.

How to make a food spray
For those intrigued by the method, here’s a summary of the food spray preparation for an area of one hectare:

Add 15 litres of boiling water to 4 kg of roughly chopped maize kernels in a container and leave to soak for 24 hours in a dark place.
Sieve, grind, and mix the soaked maize with 10 litres of cold water. Leave to ferment for 48 hours.
Filter out solids and dry them in the sun so they form a coarse powder.
To prepare the spray, mix 2 kg of powder with 5 litres of water to make a concentrate.
Filter out solids and retain the liquid.
Add 50g of chopped household solid soap, and dissolve 1 kg of sugar.

Full details can be found in the manual on the PAN UK website

I left this session buzzing with ideas. Could we adapt this idea for our own vegetable plots? Should we use a food spray on broad beans to attract ladybirds before the blackfly get established? What do you think?

Tomorrow’s climate

This discussion looked at the challenges of climate change and practical global solutions.

“If you do only one thing, collect rainwater” Bill Mollinson

First to speak was Perrine Bulgheroni of La ferme du Bec-Hellouin. Perrine is a climate hero of mine. I first heard her speak at ORFC several years ago and I love her book Miraculous Abundance, written with Charles Herve-Gruyer about their microfarm, La ferme du Bec-Hellouin, in Normandy. I have summarised her talks from two sessions as its all relevant to creating resilient spaces.

Perrine and Charles took up growing from a non farming background, beginning their journey in 2003, a time when people were aware of climate change and peak oil. Interestingly, she said that if she was starting today, it would have a focus on water and energy. Their vision was to create an edible landscape without damaging the Earth.

They designed a space that would become a natural ecosystem mimicking nature; planting trees and shrubs to give protection from the wind protection and for humidity, digging ponds for wildlife and water harvesting, and creating a space to grow food while preserving it for future generations.

Their biointensive methodology draws from the innovative Maraîcher Parisiens, the market gardeners of the 1600s, who used cloches, cold frames and horse manure to grow as many as eight crop rotations a year to feed Paris, as well as inspiration from Korea and Japan, to devise an ecosystemic approach. At Bec-Hellouin, they have created a mosaic of mini ecosystems which are key to resilience.

Perrine spoke again in a second session on Permaculture design for water independence. In this session, she talked about talked about how they were working to improve local rain water retention by:

Building a humus rich soil which means more soil life and water retention
Maintaining soil cover to reduce erosion, conserve water, encourage biodiversity and aid the local water cycle
Creating landscape features such as swales, raised beds, terraces, edges, ponds, plus planting trees and shrubs to slow water and increase infiltration

Regenerative Hydrology

The second half of Perrine’s talk focused on regenerative hydrology which involves a set of practices that aim to improve the quality of soil and water in a catchment area.

The 4 Rs are:

Receive: optimising the land to capture precipitation and enhance soil, using vegetation to boost infiltration
Recharge: Facilitate water movement into aquifers, through permeable soils so recharging the local water cycle
Retain: This is a key feature since water retention means more water is available during a dry period.
Release: Manage the gradual release of water to maintain a base flow in streams and rivers so they never run dry and support ecosystems downstream.

Perrine ended her talk by saying that the farm had experienced climate change first hand over the last 10 years. Before that they had what she called ‘normal years’ when they knew roughly what to expect. But for the last 8 years, they have had non normal seasons making it difficult to farm and complicating long term planning.

She stressed that society needs to move away from a focus on drainage to one of retention and water management.

Don’t forget that we can all do something in our spaces - even if its just collecting water or educating and becoming an advocate for change.

I’ll be covering the other speakers talking on Tomorrow’s Climate next week as they too have some inspirational ideas that are perfect for allotments and gardens.

Silvohorticulture: Integrating Trees into Crops

Another highlight of ORFC was the launch of Silvohorticulture: A Grower’s Guide to Integrating Trees into Crops by Andy Dibben and Ben Raskin. I had the privilege of editing this book, which is a game-changer for those exploring agroforestry.

This practical book offers practical guidance on growing trees with vegetables, emphasizing the many benefits, from increased biodiversity to improved soil health.

The book publishes tomorrow and you can buy it on online. If you subscribe to Chelsea Green’s newsletter you will get 25% off your first order - so please buy direct from the publisher rather than via that other place!! It will be available for preorder in the US too.

Andy is Head Grower at Abbey Home Farm, nr Cirencester and I wrote about my visit to the farm in this post: Mulching – have you tried a living mulch?

For anyone exploring resilient growing methods, the ORFC sessions were a treasure trove of ideas, solutions, and inspiration. 🌱

I will be covering more in the coming weeks but if my reports spark your interest, watch out for the recordings on YouTube in a couple of months.

Happy Gardening

Sally

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