Irrigation with wastewater and K fertilization ensure the yield and quality of coloured cotton in a semiarid climate

Authors: LIMA, BRENO - FEDERAL RURAL UNIVERSITY OF PERNAMBUCO; SILVA, ENIO - FEDERAL RURAL UNIVERSITY OF PERNAMBUCO; ZONTA, JOAO - BRAZILIAN AGRICULTURAL RESEARCH CORPORATION (EMBRAPA); NETO, CICERO - ENTERPRISE FOR TECHNICAL ASSISTANCE AND RURAL EXTENSION OF PARAIBA; LACERDA, CLAUDIVAN - UNIVERSIDADE FEDERAL DO CEARA (UFC); Ferreira, Jorge; CRUZ, FLAVIO - FEDERAL RURAL UNIVERSITY OF PERNAMBUCO

Submitted to: Agronomy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/22/2021
Publication Date: 11/23/2021
Citation: Lima, B.L.C., Silva, E.F.F., Zonta, J.H., Neto, C.P.C.T., Lacerda, C.F., Ferreira, J.F.S., Cruz, F.J.R. 2021. Irrigation with wastewater and K fertilization ensure the yield and quality of coloured cotton in a semiarid climate. Agronomy. 11(12). Article 2370. https://doi.org/10.3390/agronomy11122370.
DOI: https://doi.org/10.3390/agronomy11122370

Interpretive Summary: Although the expansion of irrigated agriculture in semiarid regions depends on affordable recycled water, the quality of this water and its effects on crop yield have not been fully investigated. Treated domestic sewage (TDS) water is cheaper than fresh water and can provide some plant nutrition, thus reducing the use of fertilizers and improving crop production, while enabling the expansion of irrigated agriculture. However, there are no data available for most crops, including colored cotton yield and fiber quality under deficit or excess irrigation with TDS, especially in combination with potassium (K) nutrition under field cultivation. This study aimed to evaluate yield components and fiber quality of colored cotton under irrigation regimens combining TDS with K fertilization. The results showed that, when compared with control treatments, irrigation with TDS can produce higher crop yields with more desirable fiber characteristics. The technology developed in this work can allow farmers to maintain or increase cottonseed yield in semiarid regions while saving on irrigation water and potassium fertilization costs.

Technical Abstract: Treated domestic sewage (TDS) can contribute to plant nutrition and improve crop production. However, there are no data for its use in coloured cotton under a deficit or excess irrigation in combination with potassium fertilization rates (KRs), mainly under semiarid tropical conditions. The research was conducted using a randomized complete block design in a factorial scheme (5 × 5, irrigation regimes vs. potassium rates), plus an additional treatment as the control ((5 × 5) + 1). The treatments consisted of five TDS irrigation regimes (50, 75, 100, 125, and 150% of crop evapotranspiration—ETC) and five KRs (0, 50, 100, 150, and 200% of the local crop recommendation), plus a control—CT— (irrigated with fresh water at 100% ETC and fertilized according to the local crop recommendation) and four replications. The optimal crop yield, water use efficiency, and potassium use efficiency were obtained when TDS was applied as a deficit irrigation treatment of 75% of ETc or as full irrigation (100% of ETC) and when associated with moderate increases in K fertilization. These treatments also resulted in a better fibre quality when compared to the CT, meeting or exceeding the requirements of the textile industry. Therefore, moderate deficit irrigation with TDS is indicated as an important strategy to save fresh water and to reduce the use of fertilizers, while having the potential to increase profit margins for cotton production in tropical semiarid regions.