OPINION: Synthetic fertilizers detrimental to Kenyan soil

Last week, President William Ruto announced the commencement of the second phase of the fertilizer subsidy program that saw the prices of fertilizer drop further to 2500 shillings, down from 3500 shillings for a 50-kg bag.

As reactions emerge across the country on the success or not of the program's first phase, it's also essential to bear in mind the effects these synthetic fertilizers have on our soil.

High use of synthetic fertilizers has tremendous effects on the health, texture and quality of the soil, affecting crop production in the long run.

They quickly boost plant growth but do little to stimulate soil life, improve soil texture, or improve soil's long-term fertility. Since they are highly water-soluble, it makes it easy for them to leach into waterways.

These synthetic fertilizers disrupt the delicate balance of soil flora and fauna, negatively affecting nutrient availability and soil structure over time.

Synthetic fertilizers undeniably contribute to increased crop yields in the short term. However, their long-term impact on soil biodiversity, including the population of beneficial microorganisms, is a growing concern.

One essential useful type of fungi that is affected by the extensive use of synthetic fertilizers is Ectomycorrhizal Fungi (EMF). These tiny but mighty organisms play a crucial role in making essential nutrients readily available to our crops.  

EMF are a group of soil fungi that form mutualistic relationships with the roots of many plant species. The fungi enhance the plant's nutrient absorption capabilities through this symbiotic relationship by extending their hyphal network deep into the soil. In return, the plant provides the fungi with a share of the carbohydrates produced through photosynthesis. This mutual exchange boosts nutrient uptake for the plant and fosters better resistance to stressors like drought and diseases. 

As we welcome the recent announcement by the president, the country needs to consider and explore other sustainable alternatives that are safe, affordable and do not harm our soil. Agroecological practices promote methods that focus on creating sustainable and balanced ecosystems.

The practice involves using ecological principles and practices that improve agricultural productivity while promoting environmental health and social well-being. It encourages crop rotation, composting, natural pest control, and using local resources to reduce reliance on synthetic inputs like synthetic fertilizers and pesticides.

Organic fertilizers, such as aerobically prepared compost, have proven to be valuable alternatives that provide essential nutrients and promote the growth of beneficial soil flora. Compost is a nutrient-rich organic material that is a haven for diverse microorganisms, including EMF.

Compost sustains these beneficial organisms when incorporated into the soil, allowing them to flourish and form symbiotic relationships with plant roots. Zero or minimum tillage practices, on the other hand, helps preserve soil's natural structure and offer a stable habitat for soil organisms, allowing them to thrive and continue their vital role in nutrient recycling. 

Furthermore, zero or minimum tillage helps prevent the disruption of the hyphal networks of EMF and other beneficial microorganisms, ensuring continued nutrient transfer to crop plants effectively. As a result, the combination of compost and zero/minimum tillage promotes soil health and fertility, leading to enhanced crop growth and yields in the long run.

With this consideration in place, there is a need to direct money into agricultural practices that are sustainable and effective. National and county governments need to allocate financial support to educational programs and training for farmers, in order to build their awareness and capacity to embrace agroecological approaches to farming. Farmers need to be educated on the benefits of these practices and their positive impact on crop productivity.

Financial incentives such as subsidies can be redirected to organic inputs and support purchasing of minimum tillage equipment to encourage farmers to transition towards agroecological practices. 

Collaborative efforts between research and government institutions, agricultural experts, and farming communities can further drive innovation and knowledge-sharing regarding the most effective ways to integrate these sustainable practices into existing farming systems.

As we celebrate and recognize the government's efforts in making fertilizers affordable and accessible to farmers, we must also recognize the long-term impact of synthetic fertilizers on our soil's health. Embracing agroecology benefits our environment and empowers our farmers to cultivate resilient and nutrient-dense crops that contribute to food security and a healthier agricultural landscape in Kenya.

By Dr. Harun Warui, PhD.
Programme Lead, Food Right and Agroecology, Heinrich Boell Foundation.