Diagnosing multiple nutrient deficiencies that limit crop growth and yield on sands in south-central coastal Vietnam

ABSTRACT

Nutrient management for profitable and sustainable crop production depends on correct diagnosis of the full range of disorders that could potentially limit crop yield and grain or fruit quality. On sands, a suite of nutrient disorders can typically limit crop yield but the specific deficiencies can vary among types of sand. Hence, for site-specific nutrient management, there is a need for accurate diagnosis of the disorders. In the present study, the omission design—‘All’ nutrients, and without phosphorus (P), potassium (K), sulfur (S), boron (B), copper (Cu), zinc (Zn) and molybenum (Mo)—was used in five field experiments to determine limiting nutrients for peanut growth and yield on a range of the major sand types in south-central coastal (SCC) Vietnam. A modified double-pot experimental approach was also used to determine its accuracy in more rapid prediction of field nutrient deficiencies. In three field experiments in Phu Cat district, Binh Dinh province, irrigated peanut yield was depressed by K, S, B and Cu deficiency. In addition, omission of Zn depressed yield in one of those fields. Omission of Mo depressed shoot dry matter (DM) of peanut in the Cat Hanh site in 2011 but not seed yield. Double-pot experiments with maize as a test plant confirmed K, S, B and Cu deficiencies in Binh Dinh sands. By contrast, in sands in Ninh Thuan province, P, K, S, Cu and Zn were deficient for peanut yield at one field site while P, K, S, B, Cu and Zn were deficient at another. The results were supported by maize plant DM and shoot nutrient concentration responses in the double-pot experiment. We conclude that nutrient disorders vary among different sands, requiring careful diagnosis for each type of sand, but parent material best explains differences in the suite of nutrient deficiencies diagnosed in each. The modified double-pot experiment predicted the same deficiencies as the field experiments, suggesting it could be used as a diagnostic tool to assess the suite of nutrient limitations expected in different types of sands, whether in Vietnam or elsewhere. Multiple nutrient deficiencies in SCC Vietnam require further research to develop integrated nutrient management approaches to overcome these deficiencies and also minimise the cost of inputs.