To study the effects of combined straw returning with organic fertilizer replacing partly chemical fertilizer on grain yield

grain quality and chemical fertilizer use efficiency in dryland maize-wheat double cropping system

From 2015 to 2020

based on a long-term field experiment conducted at Luoyang Dry Farming Experimental Station of Chinese Academy of Agricultural Sciences

since 2007. There are three treatments

i.e.

no fertilizer control (CK)

conventional application of nitrogen

phosphorus and potassium fertilizer in both maize and wheat season (NPK)

straw mulching and organic fertilizer combined with replacing 1/3 of NPK input in wheat season (SORF). The grain yields and fertilizer use efficiencies in maize

wheat and all year from 2015 to 2020

and the grain nitrogen

phosphorus and potassium contents

grain protein contents

grain protein yields of maize and wheat from 2019 to 2020

and the contents of protein and its components in grain of wheat in 2020 were investigated. The results showed that: (1) Compared with the NPK treatment

the 5-year average yield of maize under SORF treatment were increased by 10.0%. However

there was no significant grain yield difference of wheat and all year between NPK and SORF treatments(p>0.05). (2) The grain N

P

K content in maize and wheat was increased significantly with the application of fertilizer. Compared with NPK treatment

SORF significantly increased grain nitrogen content

which significantly increased in protein content and protein yield of maize grain and wheat grain by 6.7% and 17.8%

8.0% and 6.3%

respectively

and annual protein yield increased by 10.8%. (3) SORF and NPK not only increased the contents of each protein component

but also increased the ratio of glutenin/gliadin in wheat grain

and synergistically improving the protein quantity and quality in grain. Compared with the NPK treatment

SORF significantly increased the content of different grain protein component except globulin

but the increase of glutenin/gliadin ratio was not significant. (4) Compared with NPK treatment

the nitrogen agronomic use efficiency under SORF treatment were significantly increased by 54.8%

31.2% and 77.3% in maize

wheat and all year

as well as nitrogen partial productivity by 10.0%

45.6% and 20.7%

respectively

and the phosphate (potassium) agronomic efficiency and partial productivity by 31.2%

77.3% and 45.6%

55.7% in wheat and all year. Above all

SORF could not only improve the grain yield in maize

and the grain protein content

protein yield

as well as agronomic efficiency and partial productivity in maize and wheat

but also improved the contents of different grain protein components in wheat. Therefore

straw mulching combined with organic fertilizers replacing 1/3 of NPK of wheat season was the suitable fertilization model for high yield

high quality and high efficiency in the maize-wheat double cropping system of dryland region.