Efficacy of zinc and iron nutrition on growth, yield, quality and economics of castor (Ricinus communis L.) under semi-arid environment

A field experiment was carried out at CCS HAU, Regional Research Station, Bawal during the year
2022-23 and 2023-24 consisting of nine treatment combinations viz. RDF (T 1 ), RDF + 25 kg/ha
Zinc Sulphate (21% zinc) as soil application at the time of sowing (T 2 ), RDF + 25 kg/ha Ferrous
Sulphate (19% iron) as soil application at the time of sowing (T 3 ), RDF + Foliar spray of 0.5% Zinc
Sulphate solution at 30 and 60 days after sowing (T 4 ), RDF + Foliar spray of 0.5% Ferrous
Sulphate solution at 30 and 60 DAS (T 5 ), RDF + 25 kg/ha Zinc Sulphate as soil application at the
time of sowing + Foliar spray of 0.5% Zinc Sulphate solution at 45 DAS (T 6 ), RDF + 25 kg/ha
Ferrous Sulphate as soil application at the time of sowing + Foliar spray of 0.5% Ferrous Sulphate
solution at 45 DAS (T 7 ), RDF + 25 kg/ha Zinc Sulphate as soil application at the time of sowing +
Foliar spray of 0.5% Ferrous Sulphate solution at 45 DAS (T 8 ) and RDF + 25 kg/ha Ferrous
Sulphate as soil application at the time of sowing + Foliar spray of 0.5% Zinc Sulphate solution at
45 DAS (T 9 ) laid out in randomized block design with three replications. Soil of the experimental
site was sandy loam in texture low in N, P and medium in K, with slightly alkaline in reaction (pH –
7.9). The castor crop (hybrid ICH-66) was sown in second fortnight of July, 2022 and 2023 and
harvested in the last week of March, 2023 and 2024 during both the years, respectively. Pooled data
(2022-23 and 2023-24) reveal that zinc and iron either soil applied, foliar applied or both (alone or
in combination) resulted in an increase in yield attributes and yield of castor. Treatment where 25
kg/ha Zinc Sulphate soil applied followed by foliar spray of 0.5% Ferrous Sulphate solution at 45
days after sowing recorded significantly higher seed yield in comparison to RDF and RDF + 25
kg/ha Ferrous Sulphate as soil application at the time of sowing. Oil content was not influenced by
the treatments tested. All the treatments did not differ significantly among themselves in respect of
available N, P and K in soil. Higher available Zn and Fe content was found under the treatments
where iron and zinc either soil applied, foliar applied or both (alone or in combination) over RDF,
respectively. Agronomic efficiency and partial factor productivity of Zn and Fe was highest (88.7
and 350 kg/kg, respectively) under RDF + Foliar spray of 0.5% Zinc Sulphate solution at 30 and
60 days after sowing.