Push–Pull Farming Meets Insect Frass in a Boost for Yields and Carbon

One of the most successful pest-management innovations ever developed for African smallholders is about to get a nutritional and climatic upgrade. A new study published in npj Sustainable Agriculture reports that intensifying the celebrated push–pull cropping system and coupling it with insect frass biofertilization can simultaneously raise land productivity, increase the amount of protein harvested per hectare and build carbon stocks in the soil. The finding, published on 9 February 2026, arrives at a moment when farming systems across the tropics face the coupled pressures of rising food demand, degrading soils and the urgent need to store more carbon in agricultural landscapes.

Push–pull technology, originally developed by scientists working with the International Centre of Insect Physiology and Ecology and partners, is an elegant example of agroecological engineering. Farmers intercrop their cereal crop, typically maize or sorghum, with a Desmodium legume that repels or suppresses major pests while fixing nitrogen and smothering weeds, and they plant border rows of forage grasses such as Napier or Brachiaria that attract and trap stem borers and fall armyworm moths. The legume ‘pushes’ pests away from the cereal while the border grass ‘pulls’ them in, dramatically reducing damage from insects and the parasitic witchweed Striga without synthetic pesticides. The system also produces fodder, making it attractive to mixed crop–livestock households.

Yet conventional push–pull has an inherent tension. The Desmodium intercrop occupies space that would otherwise grow the cereal, so the raw grain harvest per hectare can appear lower than in a monoculture, even when the total output of grain, fodder and ecosystem services is higher. Intensification strategies aim to resolve this by optimizing plant densities, spatial arrangements and management so that the cereal component does not sacrifice yield while the legume and grass components continue to deliver their protective and soil-improving functions. The new study set out to test whether such intensified configurations, combined with an organic fertilizer derived from insects, could push the system’s performance to a new level.

Insect frass, the mixture of insect excrement, exuviae and residual feed substrate left behind by reared insects, has emerged in recent years as a promising circular-economy input. As the insect farming sector expands to supply protein for animal feed and human food, frass is generated as a low-cost by-product in large volumes. Chemically, frass combines readily mineralizable nitrogen, phosphorus and potassium with chitin from insect exoskeletons, and there is growing evidence that chitin and associated microbial communities can stimulate soil-borne beneficial organisms, suppress certain plant pathogens and enhance plant defences. Applying frass to cropland therefore turns a waste stream from insect production into a fertilizer and biostimulant, closing nutrient loops between the growing insect economy and staple food production.

The researchers combined these two threads, evaluating intensified push–pull arrangements with and without frass amendment and comparing them against conventional reference treatments. Their measurements spanned the three pillars highlighted in the study’s title: how much usable biomass and grain the land produced, how much protein that output represented for human and animal nutrition, and how much carbon the soil held. This integrated framing matters because a farming innovation that raises one metric while degrading another offers only a partial win. The headline result is that the coupled system improved all three at once, suggesting genuine synergy rather than trade-off.

From an agronomic standpoint, the mechanisms are plausible and mutually reinforcing. The leguminous Desmodium intercrop adds nitrogen-rich residues to the soil, while frass supplies an additional pulse of readily available nutrients and chitinous material that feeds the soil microbial community. Together they can lift nutrient supply above what either input delivers alone, supporting denser or better-performing cereal plants. Meanwhile the physical structure of the intensified system preserves the pest-suppression function that makes push–pull valuable in the first place, so the additional fertility is not simply consumed by insects and weeds. The result is more photosynthate captured per unit of land, and, crucially, more of it in protein-rich fractions such as grain and legume biomass.

The protein-yield dimension deserves particular attention. Food-security debates often focus on calories, but protein adequacy is a persistent challenge in many cereal-dependent regions where smallholders cannot afford animal products or pulse-heavy diets. By quantifying how much protein the coupled system delivers per hectare, the study reframes productivity in nutritional terms. If the intensified push–pull system produces comparable grain yields to fertilized monocultures while adding legume biomass that is itself protein-dense, then the whole farm output shifts toward nutritional sufficiency without requiring more land, more pesticide or more imported fertilizer.

The carbon finding links the agronomic story to the climate agenda. Agricultural soils in sub-Saharan Africa are widely depleted of organic carbon after decades of continuous cultivation, residue removal and little returned biomass. Push–pull systems return substantial root and shoot residues from three plant species rather than one, and frass amendment adds organic material directly. More carbon entering the soil than leaving it means the system can rebuild stocks over time, contributing to climate mitigation while improving soil structure, water retention and nutrient cation exchange capacity. Because soil organic carbon also underpins fertility, the carbon gain and the productivity gain are two faces of the same biophysical process, which is why the coupled approach avoids the usual yield-versus-carbon dilemma.

For policymakers and development practitioners, the study offers a template for scaling integrated innovations rather than single-input fixes. Fertilizer subsidy programmes across Africa have struggled to deliver consistent returns in degraded, rainfed systems, while pest outbreaks such as fall armyworm have exposed the fragility of chemical-dependent control in smallholder settings. A system that bundles pest suppression, weed control, fodder production, organic fertility and carbon sequestration addresses several policy goals with one intervention. The frass component additionally connects smallholders to the emerging insect-farming industry, potentially creating local markets for a by-product that insect processors currently must dispose of, and reducing dependence on imported mineral fertilizers whose prices have proven volatile.

Questions that remain open are the ones that always accompany field-scale innovation: how the coupled system performs across heterogeneous soils, rainfall regimes and farmer management styles; how frass quality varies with insect species and substrate; and how rapidly soil carbon accumulates under real farming conditions over multiple seasons. The study’s integrated evidence, however, makes a compelling case that the next generation of push–pull should not be merely pest-proof but fertility-rich and carbon-building by design. As the global search intensifies for farming models that feed people, nourish soils and draw carbon down at the same time, the marriage of an African agroecological success story with the waste streams of a rising insect economy is a combination worth watching closely.

Subject of Research: Coupling intensified push–push push–pull cropping technology with insect frass biofertilization to improve land productivity, protein yield and soil carbon stocks in smallholder systems.

Article Title: Coupling intensified push–pull technology with insect frass biofertilization improves land productivity, protein yield and carbon stocks

Article References: Omuse, E. R., Machekano, H., Mutyambai, D. M., Ogaji, S. O., Tanga, C. M., Dubois, T., Nyasani, J. O., Mudavadi, P., Subramanian, S., & Chidawanyika, F. (2026). Coupling intensified push–pull technology with insect frass biofertilization improves land productivity, protein yield and carbon stocks. npj Sustainable Agriculture, 4(1), Article 77. https://doi.org/10.1038/s44264-026-00191-4

Image Credits: AI Generated

DOI: 10.1038/s44264-026-00191-4

Keywords: push–pull technology, insect frass, biofertilizer, soil carbon, protein yield, land productivity, sustainable agriculture, smallholder farming, maize, circular agriculture, Coupling, intensified