Purpose

Soil physico-chemical properties, biomass production, and root density are considered key factors indicating soil health in an agroecosystem. The soil physico-chemical changes and plant growth (e.g., shoot biomass production and root density) in a 6-year cultivation of plant species used as green manure in a sandy soil from Tropical ecosystem, North-eastern Brazil, were investigated between July and December 2019.

Material and methods

We characterized soil physical and chemical properties, shoot biomass production, and root density under ten plant species used as green manure: Brachiaria decumbens Stapf. cv. Basilisk, Canavalia ensiformis (L.) DC, Crotalaria juncea L., Crotalaria ochroleuca G. Don, Crotalaria spectabilis Roth, Lablab purpureus (L.) Sweet, Mucuna pruriens (L.) DC, Neonotonia wightii (Wight & Arn.) J.A. Lackey, Pennisetum glaucum L., and Stilozobium aterrimum Piper and Tracy.

Results and discussion

The highest values of soil pH, exchangeable cations, CEC, and soil available water capacity were found on the plots where Poaceae plants were cultivated, whereas for H⁺+Al³⁺, C.E.C., soil available water, and soil available water capacity were found on the plots where Fabaceae plants were cultivated. On the plots where C. ensiformis and N. wightii were cultivated, we found the highest shoot dry biomass and root density, respectively. The results highlight the importance to consider plant species from both Poaceae and Fabaceae family used as green manure as soil conditioner (by promoting soil fertility, nutrient cycling, and hydraulic properties into plant root zone), and thus creating a positive plant-soil feedback.

Conclusions

Our findings suggest that (1) a consecutive green manure practice without any input of fertilizers after 6 years changed positively both soil physical and chemical properties, and improve plant growth (e.g., shoot dry biomass and root density) in tropical savanna climate conditions; and (2) by altering soil fertility, both Poaceae and Fabaceae plants used as green manure may create a sustainable cycle into the soil profile thus promoting soil health.

中文翻译：

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巴西东北部热带生态系统绿色肥料耕作系统中的土壤理化性质，生物量生产和根系密度

目的

土壤理化性质，生物量生产和根系密度被认为是指示农业生态系统土壤健康的关键因素。在巴西东北部热带生态系统的沙质土壤中，调查了六年来用作绿肥的植物种的土壤理化变化和植物生长（例如，枝条生物量生产和根系密度），该植物种用作绿肥。 2019年12月。

材料与方法

我们表征了十种用作绿肥的植物物种：Bracharia decumbens Stapf的土壤理化特性，枝条生物量生产和根系密度。简历。蛇怪属，Canavalia ensiformis（L.）DC，Crotalaria juncea L.，Crotalaria ochroleuca G. Don，Crotalaria spectabilis Roth，Lablab purpureus（L.）Sweet，Mucuna pruriens（L.）DC，Neonotonia wightii（Wight＆Arn。） Lackey，Penisesetum glaucum L.和Stilozobium aterrimum Piper和Tracy。

结果与讨论

在种植禾本科植物的土地上，土壤pH，可交换阳离子，CEC和土壤可利用水量最高，而对于H ⁺ + Al ³⁺，则发现CEC，土壤可利用水量和土壤可利用水量最高。在种植豆科植物的地块上。在种植梭状芽胞杆菌和怀氏猪笼草的地块上，我们分别发现了最高的茎干生物量和根系密度。结果突出了考虑将禾本科和豆科的植物物种用作绿肥作为土壤改良剂的重要性（通过促进土壤肥力，养分循环以及进入植物根部区域的水力特性），从而创造积极的植物-土壤反馈。

结论

我们的发现表明：（1）在热带稀树草原气候条件下，连续6年不施用任何肥料的绿肥做法积极改变了土壤的物理和化学性质，并改善了植物的生长（例如，茎干生物量和根系密度）；（2）通过改变土壤肥力，禾本科和豆科植物用作绿肥都可以在土壤剖面中形成可持续的循环，从而促进土壤健康。