Residues from black soldier fly (Hermetia illucens) larvae rearing influence the plant-associated soil microbiome in the short term

Open Access Journal; Published online: 26 Sep 2022The larvae of the black soldier fly (BSFL, Hermetia illucens) efficiently close resource cycles. Next to the nutrient-rich insect biomass used as animal feed, the residues from the process are promising plant fertilizers. Besides a high nutrient content, the residues contain a diverse microbial community and application to soil can potentially promote soil fertility and agricultural production through the introduction of beneficial microbes. This research assessed the application of the residues on plant-associated bacterial and fungal communities in the rhizosphere of a grass-clover mix in a 42-day greenhouse pot study. Potted soil was amended with BSFL residues (BR+) or conventional compost (CC+) produced by Rwandan waste management companies in parallel to residues and compost sterilized (BR-, CC-) by high-energy electron beam (HEEB) as abiotic controls. The fertilizers were applied at a rate of 150  kg N  ha−1. Soil bacterial and fungal communities in both fertilizer and soil were assessed by high-throughput sequencing of ribosomal markers at different times after fertilizer application. Additionally, indicators for soil fertility such as basal respiration, plant yield and soil physicochemical properties were analyzed. Results showed that the application of BSFL residues influenced the soil microbial communities, and especially fungi, stronger than CC fertilizers. These effects on the microbial community structure could partly be attributed to a potential introduction of microbes to the soil by BSFL residues (e.g., members of genus Bacillus) since untreated and sterilized BSFL residues promoted different microbial communities. With respect to the abiotic effects, we emphasize a potential driving role of particular classes of organic matter like fiber and chitin. Indeed, especially taxa associated with decomposition of organic matter (e.g., members of the fungal genus Mortierella) were promoted by the application of BSFL residues. Soil fertility with respect to plant yield (+17% increase compared to unamended control) and basal respiration (+16% increase compared to unamended control) tended to be improved with the addition of BSFL residues. Findings underline the versatile opportunities for soil fertility arising from the application of BSFL residues in plant production and point to further research on quantification of the described effects

Looking back and moving forward: 50 years of soil and soil fertility management research in sub-Saharan Africa

Article purchased; Published online: 02 Nov 2017Low and declining soil fertility has been recognized for a long time as a major impediment to intensifying agriculture in sub-Saharan Africa (SSA). Consequently, from the inception of international agricultural research, centres operating in SSA have had a research programme focusing on soil and soil fertility management, including the International Institute of Tropical Agriculture (IITA). The scope, content, and approaches of soil and soil fertility management research have changed over the past decades in response to lessons learnt and internal and external drivers and this paper uses IITA as a case study to document and analyse the consequences of strategic decisions taken on technology development, validation, and ultimately uptake by smallholder farmers in SSA. After an initial section describing the external environment within which soil and soil fertility management research is operating, various dimensions of this research area are covered: (i) ‘strategic research’, ‘Research for Development’, partnerships, and balancing acts, (ii) changing role of characterization due to the expansion in geographical scope and shift from soils to farms and livelihoods, (iii) technology development: changes in vision, content, and scale of intervention, (iv) technology validation and delivery to farming communities, and (v) impact and feedback to the technology development and validation process. Each of the above sections follows a chronological approach, covering the last five decades (from the late 1960s till today). The paper ends with a number of lessons learnt which could be considered for future initiatives aiming at developing and delivering improved soil and soil fertility management practices to smallholder farming communities in SSA

Advancing key technical interventions through targeted investment

Peer Revie

Early planting of cassava enhanced the response of improved cultivars to potassium fertilization in South Kivu, Democratic Republic of Congo

Cassava is the most important crop in DRC, where it is both a staple and a cash crop. Over the last years, cassava productivity seems increasingly constrained by climate disturbances. To respond to these climatic disturbances, farmers opt to adjust the planting period to spread the risk by optimizing their chances to receive the most regular rainfall in the crucial first 100 days after planting. To investigate the potential of varying cassava planting time to mitigate the effect of changes in rainfall patterns, a full-factorial field experiment was conducted in two contrasting sites in South Kivu (DRC) including Kalehe, a highland and forest region and Uvira, a dry savannah at medium altitude. Effects of three planting periods (November 2018, January 2019, and March 2019), with and without potassium nutrients (NP and NPK), were assessed on the growth parameters of two cassava cultivars, Obama (improved) and M′ Bailo (landrace). The growth parameters included stem number, stem height, score of leaf retention and leaf lobe length and width in both sites up to four months after planting (MAP). Yield data on both the above-ground (stems and leaves) and the storage roots and related harvest index was only collected in Kalehe at 12 MAP. The highest storage root yield of 47 and 14 t ha 1 for Obama and M′ Bailo respectively were achieved when the cultivars were planted in November 2018 and received NPK fertilizer. Compared to the early planted cassava (November 2018), cassava planted in January and March 2019 produced 29% and 79% fewer storage roots. Similarly, at the fourth month of each planting, growth parameters of early planted cassava were higher than those of late planted cassava although the later planted crop was exposed to more intensive and regular rains in the early stages. Hence the highest aboveground biomass was observed for Obama planted in November while the cassava planted in January and March produced 41% and 76% less above-ground biomass, respectively. Obama storage root yield represented on average 1.7 times M′ Bailo storage root yield. K in the fertilizer amendment increased the storage root yield by 14% for M′ Bailo and 20% for Obama as compared to no K fertilization. Obama had a better and more stable harvest index of 55% while the M′ Bailo was 40%. Stem number, stem height, lobe length, and stem diameter were higher for both cultivars when planted in November 2018. This study revealed that the earlier the cassava was planted, the larger the yield. Thus, deciding to delay cassava planting to expose it to more regular rains in early stages can lead to an aggravation of the adverse effects of climate change. Although this study highlights the importance of combining early planting with improved cultivars for better yields, it did not establish evidence that the application of potassium could attenuate the negative effect of climate change on cassava productivity under rainfed conditions

A practical perspective on One CGIAR: lessons from 15 years of CIALCA agricultural research for development consortium work in central Africa

There is a wind of change blowing through the sector of international agricultural research for development (AR4D), mainly as a result of comprehensive reorganisation and transformation of one of its largest players, the CGIAR. In January 2020, Food Policy published a Special Issue providing valuable external and high-level reflections, challenges and recommendations for One CGIAR. One of the papers by Coffman et al. (2020) provided five Challenges and related Recommendations to the One CGIAR

Looking back and moving forward: 50 years of soil and soil fertility management research in sub-Saharan Africa

Low and declining soil fertility has been recognized for a long time as a major impediment to intensifying agriculture in sub-Saharan Africa (SSA). Consequently, from the inception of international agricultural research, centres operating in SSA have had a research programme focusing on soil and soil fertility management, including the International Institute of Tropical Agriculture (IITA). The scope, content, and approaches of soil and soil fertility management research have changed over the past decades in response to lessons learnt and internal and external drivers and this paper uses IITA as a case study to document and analyse the consequences of strategic decisions taken on technology development, validation, and ultimately uptake by smallholder farmers in SSA. After an initial section describing the external environment within which soil and soil fertility management research is operating, various dimensions of this research area are covered: (i) ‘strategic research’, ‘Research for Development’, partnerships, and balancing acts, (ii) changing role of characterization due to the expansion in geographical scope and shift from soils to farms and livelihoods, (iii) technology development: changes in vision, content, and scale of intervention, (iv) technology validation and delivery to farming communities, and (v) impact and feedback to the technology development and validation process. Each of the above sections follows a chronological approach, covering the last five decades (from the late 1960s till today). The paper ends with a number of lessons learnt which could be considered for future initiatives aiming at developing and delivering improved soil and soil fertility management practices to smallholder farming communities in SSA

Agroecological transformation for sustainable food systems : Insight on France-CGIAR research

This 26th dossier d’Agropolis is devoted to research and partnerships in agroecology. The French Commission for International Agricultural Research (CRAI) and Agropolis International, on behalf of CIRAD, INRAE and IRD and in partnership with CGIAR, has produced this new issue in the ‘Les dossiers d’Agropolis international’ series devoted to agroecology. This publication has been produced within the framework of the Action Plan signed by CGIAR and the French government on February 4th 2021 to strengthen French collaboration with CGIAR, where agroecology is highlighted as one of the three key priorities (alongside climate change, nutrition and food systems)