Lettuces grown in consortia in agroecological agroforestry systems (SAFs) presented horizontal diameter, dry mass and number of leaves similar to those produced alone under the same conditions. This was one of the results of studies carried out by researchers from the Agroecology Center at Embrapa Meio Ambiente (SP), in partnership with the Federal University of São Carlos (UFSCar) and the Escola Superior de Agricultura Luiz de Queiroz (Esalq). The scientists' objective was to find ways to improve production factors in intercropped vegetable and green manure crops between the rows of an agroforestry system at the Embrapa Meio Ambiente Agroecological Site. Only in the experiments in full sun (without shading), the dry mass of lettuce showed a significant difference between the two systems, with the value in single cultivation higher than that in intercropped cultivation.
“Agroecological agroforestry systems (SAFs) present a combination of agricultural crop species of economic interest and species with several other functions, including green manures, which are responsible for cycling and supplying nutrients that improve the quality of soils in their areas. physical, chemical and biological aspects”, explains Embrapa researcher, Joel Queiroga.
The scientist emphasizes that vegetables have established themselves as an interesting cultivation alternative for the first years of SAFs, since they occupy small areas and have a high added economic value. The study evaluated the productive performance of irrigated lettuce in single cultivation and intercropped with arugula and radish in this type of production system and in full sun.
It was found that the association of irrigated crops promoted better use of production factors and an increase in production per unit area. “The polyculture or consortium system showed a positive interaction in the SAF and the consortium systems were advantageous in relation to the single cultivation of lettuce, by producing a greater quantity of vegetables (arugula and radish) per unit of inputs and water”, reports Laísa Hurpia, from UFSCar.
The researchers explain that conventional intensive vegetable farming tends to exploit the full potential of soil, water and inputs, to maximize production, requiring high levels of investment, which can cause negative impacts on the environment. To minimize these impacts, agroecological production systems have been adopted such as biodiverse SAFs, which combine species in the same area and time interval, providing greater optimization and better use of inputs, water and labor. This combination can be either of species aimed at food production or also for the restoration or maintenance of soil quality, such as plants that serve as green fertilizers, such as jack beans, sunn hemp, black oats, white lupine , pigeon pea, forage turnip, mucuna, millet and others.
In this area, another study between the lines of agroecological SAF aimed to evaluate the establishment of green manure plants: black oat, forage radish and sunflower intercropped under two different soil preparations. According to Queiroga, green manure is a simple and low-cost practice to recover soil fertility, by increasing the organic matter content, cation exchange capacity and nitrogen availability through biological fixation when This fertilization is made with species from the Legume family and other macro and micronutrients contributed to the soil by these species.
Furthermore, these plants improve the formation and stabilization of aggregates in water infiltration and soil aeration, they also provide improvements in the physical attributes of the soil, such as increased porosity, reduced density and greater water retention, which make soil conditions more favorable for the development of microorganisms, insects, animals and plants.
Embrapa analyst Waldemore Moriconi says that the results demonstrated that the forage turnip and sunflower species showed better establishment with more intensive soil preparation. Black oats showed better establishment with less intensive preparation.
The soil preparation considered most intensive used a mechanized brush cutter followed by a harrow, and the least intensive used only a rotary hoe. The preparations were completed with a leveling harrow with a dragging trunk before and another after sowing.
Embrapa researcher Luiz Octávio Ramos Filho, highlights the importance of the effect of types of soil preparations for the establishment of different species of green manures and the need to deepen this research to better define these consortia and soil preparations aiming for better establishment of green manures in agroecological SAFs.
Research data can be accessed in two scientific publications on the work with lettuce and about the evaluation of green manures in SAFs.
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