Can we feed the world without industrial fertilizers?

Fertilizer use has been central to global food production over the past decades. In 2019, global use reached about 189 million tonnes, a 40% increase since 2000, contributing to nearly 50% of food production growth worldwide (Food, 2021). Yet, dependencies on industrial fertilizers come with vulnerabilities: price shocks during global crises, unequal access across regions, and heavy reliance on limited reserves of phosphorus and potassium (Ariga et al., 2006). For example, fertilizer prices between 2020 and 2022 were driven by the Russia-Ukraine war  (Breisinger et al., 2022; Ververs et al., 2019) and export bans by China, echoing similar spikes during the 2008-2009 financial crisis and earlier in the 1990s (Khabarov and Obersteiner, 2017). Such shocks often trigger global food crises, raising an urgent question: Can the world feed itself without industrial fertilizers?

Organic fertilizers and their limits 

Organic systems, such as organic home gardens, food forests, and locally produced organic fertilizers, are often promoted as sustainable alternatives. Organic materials enhance soil health, biodiversity, and ecological balance (Smith et al., 2019). However, their availability is uneven, and scaling them to meet global demand is challenging (Timsina, 2018). For instance, production relying solely on cattle manure would require 16 – 33% more land and up to 10 tonnes per hectare of organic inputs annually, risking deforestation and habitat loss (Adekiya et al., 2020; Cen et al., 2020; Muller et al., 2017; Sileshi et al., 2017). Large, resource-endowed farmers may manage better under organic-only systems, while smallholders struggle to produce enough food (Kamau et al., 2018; Meemken and Qaim, 2018).

Table 1 illustrates the gap: while countries like Brazil and New Zealand produce enough livestock waste to fertilize all their arable land, regions like India and the European Union fall far short. In Europe, full reliance on organic fertilizers could reduce food production by 40% (Smith et al., 2019).

Table 1: Manure available in different countries and the approximate proportion of arable land it can support with an average application rate of 10t/ha

Urban organic waste: A Missed opportunity 

Globally, cities generate 2 billion tonnes of municipal waste annually, about half of which is organic. If the roughly 1 billion tonnes of organic waste (Kimothi et al., 2020b) were composted or processed (e.g., as in Sous-Massa, Morocco), it could yield around 53 million tonnes of fertilizer, potentially replacing 28% of industrial fertilizer demand (Burger, 2021). While promising, this requires stronger waste management infrastructure and widespread adoption of composting technologies.

Emerging technologies such as struvite crystallization recover phosphorus and nitrogen from sewage and animal wastewater (Corre et al., 2007). Struvite, a slow-release fertilizer rich in phosphorus, magnesium, and nitrogen, can recover up to 93% of phosphorus from wastewater (Rahman et al., 2014; Suzuki et al., 2006). Globally, this could reduce phosphate mining by 1.6%, offering a small but important contribution to sustainable nutrient cycles. However, economic feasibility and regulatory challenges still hinder its widespread use (Shu et al., 2006).

Slaughterhouse waste as fertilizer

Slaughterhouse byproducts, including bones, offal, and meat meal, are nutrient-rich, especially in phosphorus and calcium (Table 2). The EU alone produces 18 million tonnes of such waste annually, with the potential to replace 7% units of its phosphorus imports (Möller, 2016). Globally, around 130 million tonnes of bone and meat waste could supply about 2% of global phosphorus demand (Tóth et al., 2014).  Despite the potential, lthe ack of recycling infrastructure and risks of disease transmission restrict uptake, particularly in developing countries (Keyzer, 2010).

Table 2: Proportion of nutrient content in slaughterhouse waste

Rock phosphate reserves and regional alternatives

Phosphorus is primarily mined from rock phosphate, with 75% of reserves concentrated in Morocco and Western Sahara (Filippelli, 2018). Many countries depend heavily on imports, making them vulnerable to geopolitical disruptions (Khabarov and Obersteiner, 2018). In East Africa, deposits of Mijingu (Tanzania) and Busumbu (Uganda) offer regional alternatives (Odongo et al., 2007; Shahid et al., 2014). Their effectiveness improves when combined with organic matter or bio-inoculants, reducing dependence on imports (Ndeleko-Barasa et al., 2021; Odongo et al., 2007). Morocco’s OCP Group is also investing in fertilizer plants across Africa to localize and stabilize prices.

Rethinking Food Systems and Crop Choices

Half of global fertilizer consumption goes to cereals, with maize, wheat, and rice as the largest consumers. Maize alone accounts for 16% of global fertilizer use. Yet alternatives like sorghum, millet, cassava, and sweet potatoes demand far fewer inputs (Gemenet et al., 2016; Oseko and Dienya, 2015). For example, cassava delivers 2.7 times more caloric energy per unit nitrogen than maize (Adiele et al., 2020). Promoting these crops not only diversifies the diet but also reduces fertilizer dependence.

Plant breeding also plays a key role. Research has produced crop varieties more tolerant to low soil fertility traits, like improved root systems or symbiosis with mycorrhiza (Beebe et al., 2010). In Tanzania, for instance, improved bean varieties adapted to poor soils are already widely adopted (Crop et al., 2015). However, uptake remains low in many regions due to limited seed access and farmer training.

Soil Nutrient Stocks: Untapped Potential

Soils themselves hold significant nutrient stocks that, if managed well, could reduce fertilizer needs (Hartemink, 2005; van der Wiel et al., 2020). Conservation farming practices in Kenya, for example, have been shown to maintain higher nitrogen and potassium stocks than conventional systems (Smaling et al., 2002). Even nutrient-deficient soils often contain large reserves that can be unlocked through biofertilizers and sustainable management practices.

Table 3: Nutrient stocks for different areas in Kenya. 

Nature-Positive Solutions: Food Forests and Home Gardens

Beyond fertilizers, food forests, permaculture, and home gardens present community-based alternatives. These systems mimic natural ecosystems, integrating trees, shrubs, and perennials to provide food, fodder, and fuel while improving soil fertility. Examples like Seattle’s Beacon Food Forest and Italy’s Picasso Food Forest show the potential for communal food production in urban settings (Riolo, 2019). Home gardens, widely practiced globally, also contribute to household food security and soil enrichment, though scaling them up to national levels remains uncertain (Galhena et al., 2013; Marsh, 1998).

Conclusion

The search for alternatives for industrial fertilizers reveals no single silver bullet, but rather a combination of strategies that collectively reduce dependence on costly imports. Organic waste recycling, wastewater recovery, slaughterhouse byproducts, regional phosphate deposits, low-demand crops, improved varieties, and nature-positive systems all play a role. Estimates suggest that waste-based alternatives alone could cut global fertilizer demand by around 25%, while integrating manure use in mixed crop-livestock systems could reduce it by up to 46%.

Ultimately, adaptation must be context–specific, reflecting regional resources, crop systems, and farmer capacities. Moving forward, diversifying fertilizer sources, improving soil nutrient management, and rethinking food systems will be crucial for rebuilding resilience against future fertilizer price shocks and ensuring global food security.

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