Agro-biological and economic efficiency in a beetroot (Beta vulgaris L.) production system fertilized with hairy woodrose (Merremia aegyptia (L.) Urb.) as green manure

Abstract

Beetroot (Beta vulgaris L.) is a tuberous vegetable that is under experimentation in the vegetable production system in Rio Grande do Norte state (Brazil). It is quite demanding, in nutritional terms. One of the alternatives to meet this need is green manuring using spontaneous species of the Caatinga biome. The aim of the present work was to optimize the agro-biological performance and economic profitability of the beetroot 'Early Wonder', fertilized with different doses of hairy woodrose (Merremia aegyptia (L.) Urb.) in this semi-arid environment. Hairy woodrose is a spontaneous species of the Caatinga biome that is widely distributed, being found in forests, fences, forest clearings and fields, growing in soils of different textures, producing biomass with a high content of macronutrients. This material was collected from spontaneous vegetation, native to the region, and used as green manure.The experimental design was a randomized complete block, with four treatments and five replicates. The treatments consisted of four amounts of hairy woodrose biomass incorporated into the soil (10, 25, 40 and 55 t ha-1 of dry matter). The following agronomic characteristics were evaluated in each beetroot treatment: plant height, fresh mass of shoots, number of leaves per plant, dry mass of shoots and dry mass of roots, total and commercial root productivity, and root productivity classified into scrap and extra roots, extra A roots, extra AA and great roots. Apart from these characteristics, the following economic indicators were also determined for each treatment: gross income, net income, rate of return and profit margin. The maximum agro-biological efficiency of beet root productivity (22.68 t ha-1) was obtained from 44.92 t ha-1 of hairy woodrose biomass added to the soil. The maximum economic efficiency of the yield of beet roots was achieved as a net income of AU$2,491.00 (R$6,406.36) ha-1, provided by the production of 22.04 t ha-1 of commercial roots, using 37.03 t ha-1 of hairy woodrose biomass incorporated into the soil. The use of hairy woodrose as green manure presents agro-economic feasibility in beet cultivation in this semi-arid environment.

Beetroot and radish production under different doses of green manures

“…The results obtained in these experiments are in agreement with those obtained by Silva et al (2011) and Silva et al (2019), working with the cultivation of beetroot in monocropping, as well as those obtained by Nunes et al (2020) for radish monocropping.…”

“…For the cultivation of beetroot, the following determinations were made: plant height, number of leaves per plant, DM of shoots and roots, total and commercial productivity, and classification according to root diameter (DR): extra (DR> 4 and <5 cm), extra A (DR≥5 and <6 cm), extra AA (DR≥6 and <7 cm) and great (DR> 7 cm); cracked, bruised, forked roots or roots smaller than 4 cm are classified as scrap (Silva et al, 2019).…”

“…The productivity of great roots increased with the increase of the amounts of biomass of M. aegyptia and C. procera incorporated into the soil, in the polynomial model, reaching the maximum optimized value of 10.37 t ha -1 with 46.39 t ha -1 of biomass (Figure 2D). Silva et al (2019), studying the performance of beetroot fertilized with M. aegyptia, obtained optimized productivities of 4.44; 6.12 and 13.85 for roots extra, extra A, and extra AA plus great, respectively, with the amounts of M. aegyptia biomass of 27.09; 33.53 and 51.02 t ha -1 . These results were different from those obtained in this research, where the productivities were 1.61; 2.59 and 14.68 t ha -1 (Figures 2A, 2B and 2C), for that same root classification with the amounts of the biomass mixture of C. procera and M. aegyptia of 16; 26.37 and 49.51 t ha -1 .…”

“…Some species of the Caatinga biome are alternatives for fertilizing vegetables, due to their qualities as "good fertilizers". They provide nutrients, and have excellent biomass with low C/N ratio, which provides faster decomposition and release of nutrients for the plants (Silva et al, 2019). Hairy woodrose can produce 36 t ha -1 of green biomass containing on dry basis 2.62% N, 0.17% P, 1.20% K, 0.90 Ca and 1.08 Mg.…”

Intercropping arugula with aromatic condiment species affords better yields, biological efficiency and financial return

“…the financial gains pay for the costs incurred with the cultivation, and still give an additional return of 89% in relation to net revenue. Among the economic indicators under evaluation, profit is the one indicator that allows the producer to visualise the best intercropped system in terms of agroeconomic efficiency (Silva et al, 2019).…”