In order to explore the feasibility of straw iso-nitrogen replacement of chemical fertilizer and its effect on soil moisture and dry matter accumulation of maize

field experiments were carried out for six consecutive years. 2020 was the fifth year of fertilization

2021 was the sixth year of fertilization

and 225 kg/hm2 iso-nitrogen amount was maintained. Five fertilization treatments were set up

which were CK (single fertilizer

100% fertilizer nitrogen)

S25 (25% straw nitrogen +75% fertilizer nitrogen)

S50 (50% straw nitrogen +50% fertilizer nitrogen)

S75 (75% straw nitrogen +25% fertilizer nitrogen) and S100 (100% straw nitrogen)

and the effects of straw equal nitrogen instead of chemical fertilizer on soil water storage

water use efficiency

soil water consumption

soil nutrient and dry matter accumulation of maize were studied. The results showed that: (1) In the experiment of 2020

soil water storage in 0-80 cm soil layer was S50>S25>CK>S100>S75 before sowing and during filling stage

it was S50>S25>CK>S75>S100 in trumpet and tasseling stage. At maturity

it was S50>CK>S25>S100>S75. In the test of 2021

soil water storage in 0-80 cm soil layer was S25>S50>S100>CK>S75 in the large trumpet period. At tasseling stage

soil water storage in 0-80 cm layer was S25>S50>CK>S100>S75. (2) In the experiment of 2020 and 2021

during the whole growth period of maize growth

the variation trend of soil water storage in each layer of 0-200 cm in each treatment group with soil depth was consistent

and soil water storage of S25 and S50 treatments were larger than that of CK

while soil water storage of S75 and S100 treatments were smaller than that of CK. (3) In 2020 and 2021

compared with CK

there were no significant differences in soil water consumption and water use efficiency of each straw replacement treatment group

but in 2021

soil water consumption of S50 was significantly higher than that of S100

increased by 5.00%. (4) In the experiment of 2020

the content of soil organic matter and alkali-hydrolyzable nitrogen in each straw replacement treatment group had no significant difference compared with CK

and the content of soil available phosphorus in S100 treatment was significantly lower than that of CK by 50.75%. In 2021

compared with CK

soil organic matter content of S25

S50

S75 and S100 significantly increased by 27.40%

38.13%

36.30% and 22.60%

respectively. Soil alkali-hydrolyzable nitrogen content of S50 increased by 27.74% compared with CK. Compared with CK

soil available phosphorus content of S25

S50

S75 and S100 significantly declined by 31.48%

22.22%

30.56% and 45.68%

respectively. (5) In the experiment of 2020

in each growth period of maize

there was no significant difference in dry matter accumulation per plant treated with straw instead of chemical fertilizer compared with CK. However

in the experiment of 2021

the dry matter accumulation per plant in S50 treatment was the highest in tasseling stage

filling stage and maturity stage

with a increase by 22.39%

34.06% and 12.58%

respectively

compared with CK. Compared with CK

the dry matter accumulation per plant of S75 increased by 22.49% and 12.11%

respectively

in the filling stage and maturity stage. In general

dry matter accumulation per maize plant increased first and then decreased with the increasing of proportion of straw replacing fertilizer. In order to ensure soil moisture and nutrient

as well as dry matter accumulation

S50 was a potential way to replace chemical fertilizer under the conditions of this experiment.