Effects of intercropping planting patterns and nitrogen addition level on nitrogen absorption and biomass within oat-pea intercropping systems

doi:10.11686/cyxb2024452

Abstract

Abstract:

Oats intercropped with peas has been regarded as an important method to improve the productivity of artificial grassland. Similarly， nitrogen fertilization is also recommended as an effective cultivation practice in increasing forage productivity for artificial grasslands. However， few studies have examined the interactive effects of different intercropping planting patterns and nitrogen addition levels on forage yields and the capacity for nitrogen absorption in oat-pea intercropping systems. A field experiment was carried out to examine the role of different intercropping patterns （monocropping， mixed monocropping， alternate-row intercropping） and nitrogen addition （control， low and high level） in improving forage biomass and increasing nitrogen uptake within intercropping systems comprising oats and peas. Our results showed 1） Both above- and belowground biomass of oats was highest when oats were intercropped with peas in an alternate-row pattern. Conversely， oat above- and belowground biomass was minimum when peas and oats were combined in a mixed intercropping system. Furthermore， both oat leaves and stem and oat root total nitrogen content and soil available nitrogen content were significantly increased when oats were intercropped with peas， while root nitrogen and soil available nitrogen contents of peas were lowest when peas were cultivated as a monocrop. 2） Root total nitrogen contents of oats and peas when monocropped were significantly higher than in the counterpart plants in alternate-row intercropped plantings. By contrast， soil NH₄⁺-N and NO₃^--N contents of oats and peas in mixed intercropped plantings were markedly higher than those in monocropped and alternate-row intercropped systems. 3） Structural equation model （SEM） results indicated that intercropping and nitrogen addition both had a positive effect on oat biomass accumulation and enhanced nitrogen absorption in leaves， stems and soil， while resulting in negative effects on pea biomass and nitrogen contents in aboveground tissues and soil. In conclusion， the forage productivity of artificial grasslands in alpine regions achieves maximum productivity when exploiting the interactive effects of oat alternate-row intercropping with peas， with the addition of a low amount of nitrogen fertilizer （50 kg·ha^-1）. Our findings suggest that grass intercropping with legumes together with modest exogenous nitrogen addition is an ideal cultivation practice to enhance the productivity of artificial grassland in alpine regions.

Key words: oats, pea, intercropping, nitrogen addition, nitrogen absorption

Gen-sheng BAO, Yuan LI, Xiao-yun FENG, Qian ZHAO. Effects of intercropping planting patterns and nitrogen addition level on nitrogen absorption and biomass within oat-pea intercropping systems[J]. Acta Prataculturae Sinica, 2025, 34(11): 161-173.

Figures/Tables 9

Fig.1 Average temperature and precipitation in different months of the pilot area in 2022

Table 1 Results of two-way ANOVA of different intercropped planting patterns and nitrogen addition levels on aboveground and belowground biomass of oats and peas

处理 Treatment	自由度 Degree of freedom	地上生物量Aboveground biomass				地下生物量Belowground biomass
		燕麦Oat		豌豆Pea		燕麦Oat		豌豆Pea
		F	P	F	P	F	P	F	P
间作种植模式Intercropping planting patterns （I）	2	7.84	<0.01	23.26	<0.01	8.40	<0.01	17.82	<0.01
氮添加水平Nitrogen （N）	2	17.46	<0.01	21.21	0.01	106.94	<0.01	1.89	0.17
间作种植模式×施氮水平（I×N）	4	3.63	<0.01	8.43	0.01	3.63	<0.01	1.23	0.32

Fig.2 Effects of nitrogen addition levels on aboveground and belowground biomass of oats and peas among different intercropped planting patterns

Table 2 Results of two-way ANOVA of total nitrogen content in stems and leaves， roots of oats and peas with combined effects of different intercropped planting patterns and nitrogen addition levels

物种 Species	处理 Treatment	自由度 Degree of freedom	茎叶全氮含量 Total nitrogen content of stems and leaves		根系全氮含量 Total nitrogen content of roots
物种 Species	处理 Treatment	自由度 Degree of freedom	F	P	F	P
豌豆Peas	间作种植模式 Intercropping planting patterns （I）	2	9.87	<0.01	45.61	<0.01
	氮添加水平 Nitrogen （N）	2	4.75	<0.05	10.76	<0.01
	间作种植模式×施氮水平（I×N）	4	28.44	<0.01	18.96	<0.01
燕麦Oats	间作种植模式 Intercropping planting patterns （I）	2	37.23	<0.01	5.37	<0.01
	氮添加水平 Nitrogen （N）	2	4.00	<0.05	36.00	<0.01
	间作种植模式×施氮水平（I×N）	4	11.17	<0.01	6.75	<0.01

Fig.3 Effects of nitrogen addition levels on total nitrogen contents in stems and leaves and roots of oats and peas among different intercropped planting patterns

Table 3 Results of two-way ANOVA of soil nitrogen content under different intercropped planting patterns of oats and peas combined with nitrogen addition levels

处理 Treatment	自由度 Degree of freedom	土壤全氮含量 Total nitrogen content in soil		土壤铵态氮含量 NH₄⁺-N content in soil		土壤硝态氮含量 NO₃^--N content in soil
处理 Treatment	自由度 Degree of freedom	F	P	F	P	F	P
间作种植模式 Intercropping planting patterns （I）	2	2.96	<0.05	3.83	<0.05	26.37	<0.01
氮添加水平 Nitrogen （N）	2	1.01	0.37	6.50	<0.01	53.82	<0.01
间作种植模式×施氮水平（I×N）	4	1.32	0.26	5.22	<0.01	7.96	<0.01

Fig.4 Effects of nitrogen addition on total nitrogen， NO3--N and NH4+-N contents of soil in different intercropped patterns between oats and peas

Fig.5 Redundancy analysis （RDA） of biomass and nitrogen contents in oats （a） and peas （b） with intercropping patterns and nitrogen addition

Fig.6 Structural equation model （SEM） based on effects of nitrogen addition levels and intercropped planting patterns on shoots （including stems and leaves）， root and soil nitrogen contents and above- and belowground biomass of oats and peas

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