Boosting Crop Yields and Farm Profits for Small Farmers Using Green Manures

Jenn Hoskins
28th July, 2024

Boosting Crop Yields and Farm Profits for Small Farmers Using Green Manures

The study was conducted in the Kadahenda cell within the volcanic highlands of Rwanda, an area characterized by a temperate climate and two distinct rainy seasons that directly influenced the observed crop responses to soil fertility treatments.

Image adapted from: Musana et al. / CC BY (Source)

Key Findings

  • In Nyabihu District, Rwanda, combining Alnus acuminata green manure (AGM) with inorganic fertilizer significantly increased maize and bean yields by up to 87% compared to unfertilized plots
  • The combination of AGM and inorganic fertilizer was the most profitable for potato farmers, showing the highest value-to-cost ratio (VCR) of 24.6
  • Despite the benefits, the VCR for maize and beans was lower, indicating economic challenges for farmers growing these crops due to low crop prices
Decline in soil fertility is a significant threat to land productivity and food security in the East African highlands. To address this issue, a study was conducted by the Rwanda Water Resources Board[1] in Nyabihu District of Rwanda from 2013 to 2016. The research aimed to evaluate the effects of Alnus acuminata green manure (AGM) on the productivity and profitability of maize (Zea mays), beans (Phaseolus vulgaris), and potato (Solanum tuberosum). The treatments included application of AGM alone, inorganic fertilizer alone, a combination of AGM and inorganic fertilizer, and an unfertilized control plot. The study found that the combination of AGM and inorganic fertilizer resulted in the highest yield increases for maize (44%) and beans (46%) compared to inorganic fertilizer alone. When compared to the unfertilized control, the yield increase was even more pronounced, reaching up to 87%. This suggests that the integrated use of organic and inorganic fertilizers can significantly boost crop productivity. Financial analysis revealed that the combination treatment recorded the highest value-to-cost ratio (VCR) of 24.6 for potato, indicating a substantial potential for increasing the incomes of potato farmers. However, the VCR for maize and beans was significantly lower at 2.9, suggesting that the practice might be less appealing for farmers growing these crops due to low crop prices. The findings align with previous studies that have shown the benefits of combining organic and inorganic fertilizers. For instance, a meta-analysis on maize[2] indicated that combining mineral and organic fertilizers leads to greater productivity and agronomic efficiency compared to sole applications. This synergy is particularly effective when high-quality organic matter is used alongside significant quantities of nitrogen. Similarly, the current study's results are consistent with findings from research on common beans in Zimbabwe[3], which demonstrated that co-application of nitrogen and phosphorus significantly increased grain yields, especially in non-degraded soils. The study's methodology involved comparing the different treatments across two seasons and on soils with medium and high fertility levels, as defined by the farmers' knowledge and experience. This local expertise was validated by soil analysis, ensuring that the experimental design was grounded in practical realities. Crop yields were analyzed using a linear mixed model, while other parameters were evaluated using descriptive statistics. The comprehensive approach of combining AGM with inorganic fertilizers not only boosts crop yields but also offers a sustainable solution to soil fertility decline. This is crucial for the East African highlands, where soil degradation and low productivity are pressing issues. The study's findings suggest that adopting integrated soil fertility management practices can significantly enhance food security and farmer incomes in the region. However, the study also highlights the economic challenges associated with such practices. While the combination of AGM and inorganic fertilizers is highly profitable for potato farmers, the lower VCR for maize and beans indicates that market conditions and crop prices play a critical role in the adoption of these practices. This underscores the need for supportive policies and market interventions to make integrated soil fertility management more attractive and feasible for farmers growing a variety of crops. In conclusion, the study conducted by the Rwanda Water Resources Board provides robust evidence that integrating organic and inorganic fertilizers can significantly improve crop productivity and profitability. This approach not only addresses the immediate issue of soil fertility decline but also offers a sustainable pathway for enhancing food security in the East African highlands. The findings build on previous research[2][3] and offer valuable insights for policymakers, researchers, and farmers aiming to adopt climate-smart agricultural practices.

AgricultureSustainabilityPlant Science

References

Main Study

1) Enhancing crop productivity and its economic farm profitabilty of smallholder farmer through the use of green manures from Alnus acuminata

Published 27th July, 2024

https://doi.org/10.1186/s43170-024-00271-w

Related Studies

2) Combining organic and mineral fertilizers as a climate-smart integrated soil fertility management practice in sub-Saharan Africa: A meta-analysis.

https://doi.org/10.1371/journal.pone.0239552

3) Response of common bean (Phaseolus vulgaris L.) to nitrogen, phosphorus and rhizobia inoculation across variable soils in Zimbabwe.

https://doi.org/10.1016/j.agee.2018.08.010


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