Effects of Nitrogen Application Depth on Water Consumption Characteristics and Dry Matter Accumulation and Distribution in Rainfed Wheat

Abstract

To raise a suitable nitrogen application depth for rain-fed wheat in the Yellow-Huai Rivers Zone in China,we tested the water consumption characteristics and dry matter accumulation amounts and distribution ratios of wheat cultivars Shannong 16 and Yannong 0428 under different nitrogen application depths in 2010-2011 and 2011-2012 growing seasons.The nitrogen application depths were designed in four levels,which were surface application(D1) and application depths of 10 cm(D2),20 cm(D3),and 30 cm(D4).Compared to D1 and D2,D3 and D4 exhibited significantly greater water consumption amounts in the periods of jointing-anthesis and anthesis-maturity and soil water consumption amounts in 40-120 cm soil layers(P 0.05).In the 2011-2012 growing season with sufficient precipitation,the 120-160 cm soil water consumption amounts of D3 and D4 treatments were 4.0-5.3 mm greater than those of D1 and D2(P 0.05).These results indicated that nitrogen applied in 20-30 cm of soil depth could increase the utilization of soil water,particularly deep soil water,to meet the water requirement of wheat plant after jointing stage.Besides,D3 and D4 treatments also showed dramatically higher dry matter accumulation amounts from jointing to maturity than D1 and D2 treatments(P 0.05).After anthesis,the dry matter accumulation amounts in D3 and D4 were 394.5-723.1 kg ha 1 higher than those in D1 and D2,and at maturity stage,the increments were 642.1-2006.8 kg ha 1.The grain yields and partial factor productivities of nitrogen in D3 and D4 were significantly higher than those in D3 and D4,and no significant difference between D3 and D4.Besides,D3 had relatively higher water use efficiency.Therefore,we suggest that 20 cm is the optimal soil depth of nitrogen fertilizer application for rain-fed wheat in Huang-Huai Rivers Zone.