Yield Advantage And Nutrient Utilization Of Intercropping In Northwest China

Studies demonstrated that intercropping planting has obvious advantages in crop yield and nutrient acquisition. Effects of nutrient and utilization on yield advantage of new intercropping systems are rarely explored in Northwest China. A field experiment of two years was carried out to investigate dynamic law of nutrient uptake and utilization, biomass accumulation, and yield advantage of intercropping systems of maize/potato, maize/rapeseed, soybean/potato, soybean/rapeseed and potato/rapeseed in Northwest China. The main results were as follows:(1) Intercropping systems have yield advantage and nutrient uptake advantage, maize/potato, maize/rapeseed, soybean/potato and soybean/rapeseed had yield advantages with a land equivalent ratio (LER)>1, also potato/rapeseed intercropping systems had a yield disadvantage with a land equivalent ratio (LER)<1. Grain yields of maize/potato intercropping were increased by 15%, compared to corresponding sole cropping systems. Maize/rapeseed intercropping significantly enhanced grain yields by 13%, P uptake by 22%, K uptake by 43%. Soybean/potato intercropping significantly enhanced grain yields by 22%, N uptake by 55%, P uptake by 33%, K uptake by 26%. Soybean/rapeseed intercropping significantly enhanced grain yields by 78%, N uptake by 72%, P uptake by 80%, K uptake by 74%.(2) The dynamic biomass accumulation and nutrient accumulation of crop could be described by Logistic curve equation. Compared with sole crop, intercropping significantly enhanced the maximum biomass accumulation and the maximum nutrient accumulation. In maize/potato intercropping systems, intercropped maize significantly enhanced maximum biomass accumulation by 56%-116%; compared to corresponding sole crop, intercropped potato significantly enhanced maximum biomass accumulation by 16%-54%, intercropped potato significantly enhanced maximum NK nutrient accumulation by 21%-97%. In maize/rapeseed intercropping systems, intercropped rapeseed significantly enhanced maximum NP nutrient accumulation by 40%-51%, compared to corresponding sole crop. In soybean/potato intercropping systems, intercropped soybean significantly enhanced maximum NPK nutrient accumulation by 22%-259%, compared to corresponding sole crop. In soybean/rapeseed intercropping systems, intercropped soybean significantly enhanced maximum biomass accumulation by 33%-49%, and significantly enhanced maximum NPK nutrient accumulation by 41%-78%, compared to corresponding sole crop,(3) Intercropping delayed the time at which the crop with weak competitive attained its maximum instantaneous per capita rate of biomass production, also delayed the time at which the two crops attained its maximum instantaneous per capita rate of nutrient accumulation. In maize/potato intercropping systems, the time of maximum instantaneous per capita rate of biomass production was delayed for 21-41d for intercropped maize compared with corresponding sole crop; the time of maximum instantaneous per capita rate of NPK nutrient accumulation was delayed for 15-21d and for 10-18d for intercropped maize and intercropped potato compared with corresponding sole crop, respectively. In maize/rapeseed intercropping systems, the time of maximum instantaneous per capita rate of biomass production and NPK nutrient accumulation was delayed for 28-33d and 27-38d for intercropped maize, respectively; the time of maximum instantaneous per capita rate of PK nutrient accumulation was delayed for 6-16d for intercropped rapeseed. In soybean/potato intercropping systems, the time of maximum instantaneous per capita rate of biomass production and NP nutrient accumulation was advanced for 5d and 8-12d for intercropped soybean, respectively; the time of maximum instantaneous per capita rate of K nutrient accumulation was delayed for 16d for intercropped potato. In soybean/rapeseed intercropping systems, the time of maximum instantaneous per capita rate of biomass production and NPK nutrient accumulation was delayed for 17-41d and 10-40d for intercropped soybean, respectively, the time of maximum instantaneous per capita rate of K nutrient accumulation was delayed for 11d for intercropped rapeseed.(4) Effects of intercropping systems of maize/potato, maize/rapeseed, soybean/potato, soybean/rapeseed on nutrient utilization were weak. Yield advantage of intercropping was mainly attributed to the enhanced nutrient uptake.