Precision N Management by LCC and SPAD Affecting Growth, Productivity and Economics of Maize

Abstract

Conventional methods based on soil tests and plant tissue analyses result in good yields, but these are often time-consuming and expensive. Precision diagnostic tools such as the leaf colour chart (LCC) and soil plant analysis development (SPAD) meter are presently available for site-specific and need-based N management in cereals; these tools can estimate the N status of growing crops and help increase nutrient availability based on plant needs, resulting in greater plant growth and productivity. In view of this, a field experiment was conducted during the rabi season of 2023-24 at Assam Agricultural University, Jorhat, to evaluate the effect of nitrogen management through precision tools on the growth and yield of maize (variety DKC 9081). The experiment was laid out in a randomised block design with 3 replications and ten treatments, viz., vermicompost @1.5 t/ha + RDN @ 80kg /ha, vermicompost @ 1.5 t/ha + SPAD value ≤ 30 @ 20 kg N/ha, vermicompost @ 1.5 t/ha + SPAD value ≤ 32.5 @ 20kg N/ha, vermicompost @ 1.5 t/ha + SPAD value ≤ 35 @ 20kg N/ha, vermicompost @ 1.5 t/ha + SPAD value ≤ 37.5 @ 20kg N/ha, vermicompost @ 1.5 t/ha + SPAD value ≤ 40 @ 20kg N/ha, vermicompost @ 1.5 t/ha + LCC ≤ 3.5 @ 20kg N/ha, vermicompost @1.5 t/ha + LCC ≤ 4 @ 20kg N/ha, vermicompost @ 1.5 t/ha + LCC ≤ 4.5 @ 20kg N/ha and control. The results revealed that the different nitrogen management practices under study influenced crop growth parameters, yield attributes and yield of rabi maize. Among the treatments, vermicompost @ 1.5 t/ha + LCC ≤ 4.5 @ 20kg N/ha and vermicompost @ 1.5 t/ha + SPAD value ≤ 40 @ 20kg N/ha recorded higher values for crop growth parameters such as plant height, number of fully developed leaves, leaf area index, root parameters, plant dry weight, crop growth rate and relative growth rate. The same treatments showed higher maize yields, with respective increases in cob yield by 120.65 and 114.89%, kernel yield by 153.33 and 152.23%, and stover yield by 69.27 and 67.94% over the control. The benefit-cost ratio was also higher under vermicompost @ 1.5 t/ha + LCC ≤ 4.5 @ 20 kg N/ha (1.99) and vermicompost @ 1.5 t/ha + SPAD value ≤ 40 @ 20kg N/ha (1.97).