Enhancing lowland rice physiology with integrated nitrogen nutrient sources in Nigeria’s derived savannah

Nitrogen is an essential nutrient for optimal rice growth and yield. Many Nigerian rice fields encounter difficulties in their production process because of insufficient nitrogen in the soil leading to reduced crop yields. However, the sole reliance on expensive inorganic nitrogen fertilizers is economically challenging for small farmers in Nigeria’s derived savannah. Therefore, integrated approaches to nutrient management have been put into practice to reduce the adverse effects of climate change and improve crop productivity in lowland rice cultivation. We aimed to investigate the impact of integrated nutrient inputs on the performance of NERICA L-34 and ARICA 3 rice varieties during the years 2017, 2018, and 2019. Various treatments were administered, namely 100 kg of nitrogen/ha (NPK), 75 kg/ha (NPK) + 25 kg/ha (manure), 50 kg/ha (NPK) + 50 kg/ha (manure), 25 kg/ha (NPK) + 75 kg/ha (manure), and 100 kg/ha (manure). A control group was samples without fertilizers. Key physiological parameters were assessed, including partial factor productivity, nitrogen uptake, nitrogen utilization efficiency, nitrogen internal utilization efficiency, physiological efficiency, recovery efficiency, total leaf area index, chlorophyll content, as well as root fresh and dry weights. Our research followed a randomized complete block design with a split-plot arrangement, replicated three times. The data underwent analysis of variance and the Duncan multiple range test (with a significance level set at p ≤ 0.05), and GENSTAT was used to compare the physiological traits of the rice varieties. Our findings revealed that the combination of 75 kg/ha (NPK, inorganic) and 25 kg/ha (manure, organic) significantly enhanced nutrient recovery and uptake in the NERICA L-34 rice variety, resulting in improved nitrogen absorption. While the ARICA 3 variety consistently exhibited higher chlorophyll content, especially with the application of 100 kg nitrogen/ha (organic), NERICA L-34 displayed superior overall nutrient absorption, recovery, and nitrogen utilization. Therefore, we recommend that rice farmers prioritize cultivating NERICA L-34 for its high productivity and potential for sustainable rice farming. Our findings can also guide farmers towards feasible integrated soil fertility management practices to enhance nutrient utilization efficiency, reduce environmental impact, and contribute to sustainable rice production in the derived savannah region of Nigeria.