Manganese fertilization for sweet cassava production under organic management system

Abstract

Organic management farms in the Federal District, Brazil, usually present overlimed and overfertilized soils, with high content of organic matter and high pH. These conditions lead to a low availability of manganese to crops. Many sweet cassava (Manihot esculenta Crantz.) crops were diagnosed with Mn deficiency in the region, presenting low yields. In order to overcome such condition, an experiment was established comprising the following treatments: application of MnSO4 banded in rows; treatment of cassava cuttings with a MnSO4 solution before planting; application of MnSO4 and elemental sulfur (S0) banded in the rows, to acidify the soil, increasing the Mn solubility; and leaf spraying of a Mn solution. The best results were revealed when the Mn was applied by foliar spraying and using a combination of methods (treatment of cassava cuttings with Mn, and Mn and S0 applied to the soil before planting). This treatments provided a fresh root yield of 19.5 Mg ha-1, contrasting with the control treatment (3.6 Mg ha-1).

Sulfur-improved manganese fertilization for sweet cassava under an overlimed organic management system

“…The application of banded 4.28 kg ha -1 of Mn, alone, is non-responsive (Marchi et al 2021). That study also showed that the combination of MnSO4 application banded in soil along with elemental sulfur (S 0 ), or other methods, such as foliar application, and stem cuts treated with MnSO4, improved Mn availability for plants.…”

“…The sweet cassava (Manihot esculenta Crantz) cultivar IAC 576-70, known as "Japonesinha" was selected for its excellent culinary properties (Fialho et al 2009), and for showing severe interveinal chlorosis in leaves and low yield when under Mn deficiency stress in prior experiments (Fialho et al 2020, Marchi et al 2021.…”

“…crops grown in farms under organic management in the Federal District, Brazil, may exhibit manganese deficiency. This deficiency is characterized by the interveinal chlorosis of upper and middle leaves, causing low crop yield (Fialho et al 2020, Marchi et al 2021. The low availability of Mn is caused by the frequent and excessive use of soil amendments (usually excess of lime, poultry manure, and thermal phosphate fused with magnesium silicate and micronutrients, with alkalizing properties).…”

“…Despite the abundance of Mn in the soil, exceeding, by far, 5.0 mg Mn dm -3 , its availability to plants is highly constrained when soils pHwater is above 6.5. Though, chemical methods used to estimate the Mn availability to plants, such as DTPA-TEA pH 7.3, HCl 0.1 mol L -1 , Mehlich-1 and 3, might not reveal the real Mn availability status for plants (Marchi et al 2021). Soil tests do not appear to be able to predict the likelihood of limitations associated with Mn deficiencies or toxicities induced by pH and pE (Robson 1988) and, in addition, by rootinduced changes in chemical and microbial properties in the rhizosphere (Marshner 1988).…”

“…The authors showed important results related to the increase of cassava yield in high pH soils. According to Marchi et al (2021), more research must be developed to overcome the Mn deficiency in cassava cultivated in high pH soils, specially using higher S 0 fertilization doses than the previously studied. The use of acidifying supplements, such as S 0 , may increase Mn availability in the soil.…”