Increasing Calcium and Decreasing Nitrogen Fertilizers Improves Peanut Growth and Productivity by Enhancing Photosynthetic Efficiency and Nutrient Accumulation in Acidic Red Soil

Abstract

Excessive nitrogen and insufficient calcium could significantly impact peanut yields. This study investigated the effects of nitrogen and calcium fertilizers on nutrient absorption, utilization, and yield; experiments were conducted using the peanut cultivar from Xianghua 2008 in a split-plot arrangement with two calcium fertilizer levels (Ca0: 0 and Ca1: 568 kg CaO ha−1) in the main plots and six nitrogen fertilizer gradients (N0: 0, N45.0: 45.0, N90.0: 90.0, N112.5: 112.5, N135.0: 135.0, and N157.5: 157.5 kg N ha−1) in subplots between 2015 and 2016 in Changsha, China. We examined the impact of different rates of calcium and nitrogen fertilizers on the net photosynthetic rate (Pn), agronomic traits, dry matter quality, yield and yield composition, nutrient accumulation, and distribution. The combined application of calcium and nitrogen fertilizers significantly affected the yield and yield components, Pn, main stem height, dry matter, and nutrient accumulation. Under the same calcium level, nitrogen application significantly increased the main stem height and Pn and promoted the accumulation of dry matter and nutrients in the plant, particularly in the kernel. Under the same nitrogen treatment, calcium significantly increased Pn and promoted the accumulation of dry matter, calcium, and magnesium. The pod yield increased gradually with an increasing nitrogen application rate (0–112.5 kg ha−1) and peaked at N112.5, increasing by 52.3–138.0% compared with N0. However, excessive nitrogen application (N > 112.5 kg ha−1) decreased the pod yield. Under different nitrogen fertilizer levels, calcium application increased pod yields by 11.5–29.6% by promoting Pn, nutrient uptake, accumulation in the individual plant, and nutrient accumulation in the kernel. Therefore, this study suggested that adjusting the calcium (568 kg ha−1) and nitrogen (112.5 kg ha−1) fertilizer rates significantly improved peanut growth and productivity by enhancing photosynthetic efficiency and nutrient accumulation in calcium-deficient acidic red soil.