We are using Inga to restore soils to productivity because of its ability to grow rapidly in, and improve the fertility of compacted, acidic and nutrient poor soils. This is depends on its ability to form an association with Rhizobia bacteria in the soil which, in return for shelter and some sugar, convert nitrogen in the air to a form which promotes plant growth in the soil. This association takes the form of small nodules on the roots (see image below) which act as mega bacteria colonies. If our seedlings are to restore soils to productivity then it is essential that we help them form these associations. In the pod the seeds are not in contact with Rhizobia bacteria and in the wild inoculation would occur only when the seed falls to the ground and comes into contact with the soil. Continue reading How to inoculate Inga seeds prior to planting
It is now three months since we sowed our first seed and most of the seedlings are now 40 cm tall and ready for planting out. Together with Terry Pennington I am planning to travel to Bolivia in a couple of weeks where with Peruvian Jaime Leon we will assist with establishing the first Inga agroforest plot in the Amazon. The only problem is that most of the community members are deep in the forest harvesting Brazil Nuts!
Inga seeds have no dormant stage and germinate directly . In addition the trees fruit for a short period of time, maybe only a couple of weeks and the fruit are very popular with monkeys and parrots. This means that it is not always possible to find seed for sowing unless you are living close to appropriate seed trees and get to them before the monkeys or parrots. It is, however, often easy to find large numbers of young seedlings growing under the parent trees as parrots and monkeys have to shell the pods to extract the sweet covering on each seed and so tend not to stray too far. We therefore decided to evaluate the potential of these ‘wild’ seedlings for establishing agroforest. Continue reading Assessing the use of wild seedlings for agroforestry
Our strategy for choosing the Inga species that we are trialing is to focus on native species. This ensures that we maximize the biodiversity that will associate with the trees once established. It also avoids the risk of introducing an exotic species which then becomes an invasive weed. We are lucky in that there are over 300 species of Inga in Latin America and well over 20 within the Bolivian Amazon. While we may look spoilt for choice we do, however, need to ensure that the species we select are fast-growing, have thick relatively large leaves and will grow to become medium-sized trees. Continue reading The Inga species that we are trialing
It is over two months since we planted our first seeds and after a good start our seedlings are thriving despite the unwanted attention of crickets. Some of the seedlings are now 35 cm tall and will be ready to plant out within a few weeks.
As Inga has never before been trialed for agroforestry in the Amazon it is important that we record the scale and different causes of mortality to inform other attempts. This is done by Rolman Velarde our chief engineer on the ground in Bolivia together with each community. The main cause of mortality so far has been the failure of ca 8% of seedlings to germinate, probably because we are still learning how to optimize the processing of seed. Surprisingly the consistent second cause of mortality is the very neat and precise decapitation of seedling by what our communities think are crickets. Continue reading Inga seedling nursery: the main causes of mortality
Whilst Inga grows well in very acidic degraded and poor soils these are not the best soils to start seedlings off in a nursery prior to planting them out. We want to produce strong vigorous seedlings that will have the best start that they can when they are planted out in the poor degraded soils that they are set to restore. Continue reading Making a seed nursery in the Amazon: preparing the soil
We are planning to trial three or four native species of Inga, the most common of which is the domesticated Inga edulis. Because we want to develop the approach in a way that can be easily be replicated by our partner communities we source seed locally. Inga seeds are known as recalcitrant seeds, that is they have no dormant stage as most seeds do and so cannot be stored for any length of time. So the seeds strategy is to hit the ground running and it is not uncommon for the seeds to germinate in the pod. It also means that we need to sow the seeds within 48 hours of harvesting them. Continue reading How to prepare Inga seeds for sowing