In order to provide the basis for the application and popularization of control-release urea (CRU) in fresh edible maize

field experiments were conducted to study the effects of CRU applied in different depth (0

5

10 and 15 cm) on yield

dry matter accumulation

nitrogen utilization efficiency of fresh edible maize and inorganic nitrogen content in soil. The results showed that different application depth of CRU mainly affected the dry matter accumulation during the periods of tasseling to harvesting

moreover fertilizing CRU in 10 cm and 15 cm depth produced significant greater dry weight than fertilizing in 0 cm and 5 cm depth. Fresh ear yield

total nitrogen uptake of plants during milk ripening period

partial factor productivity (PFP)

agronomic efficiency (AE) and apparent recovery efficiency (RE) of nitrogenous fertilizer all increased with the increasing of CRU application depth. Compared with fertilizing in 0 cm

fertilizing CRU in 5 cm depth had no effect on fresh ear yield

total nitrogen uptake

PFP

AE and RE of nitrogenous fertilizer. Fertilizing CRU in 10 cm depth significantly increased total nitrogen uptake and RE. However

fertilizing CRU in 15 cm depth significantly increased fresh ear yield and total nitrogen uptake by 13.3% and 53.0%

respectively

and increased PFP from 70.9 kg/kg to 80.4 kg/kg

increased AE from 6.8 kg/kg to 16.3 kg/kg

and increased PE from 3.3% to 33.7%. The results of leaf photosynthetic characteristics determination during tasseling stage indicated that application of CRU could increase the leaf area per plant

leaf area index and the photosynthetic rate of ear leaf. Moreover

compared with the 0 cm fertilization

fertilizing CRU in 15 cm depth increased the leaf area per plant

leaf area index

photosynthetic rate

transpiration rate and intercellular CO2 concentration of ear leaf. The results of soil inorganic nitrogen test at key growth stages indicated that the increasing of CRU application depth significantly increased inorganic nitrogen content in 0 - 20 cm soil layer of fertilizer band at jointing

tasseling and harvest stages

and increased it in 20 - 40 cm soil layer of fertilizer band at tasseling and harvest stages

and increased it in 0 - 20 cm soil layer of non-fertilizer band at harvest stage. These results indicated that deep application of CRU could significantly improve the soil nitrogen supplying ability and leaf photosynthetic characteristics after tasseling stage

and promote dry matter accumulation and nitrogen absorption

and thus improve yield and nitrogen utilization efficiency of fresh edible maize. Under the conditions of this study

the optimal application depth of CRU was 15 cm for fresh edible maize.