Maize-soybean relay cropping increases soybean yield synergistically by extending the post-anthesis leaf stay-green period and accelerating grain filling

Relay cropping of Poaceae and Fabaceae promotes high yield and land-use efficiency by allowing a double harvest.However,it is difficult to increase yield synergistically because of the reduced photosynthetic abilities of legume leaves under the shade of graminoids.Leaf photosynthetic capacity in relay cropping systems is associated with ecological niche differentiation and photosynthetic compensation after restoration of normal light.We conducted a field experiment in southwest China in 2020–2021 to evaluate the effects of three cropping patterns:maize–soybean relay cropping(IMS),monoculture maize(MM),and monoculture soybean(SS),and N application levels:no N application(NN:0 kg N ha^(−1)),reduced N(RN:180 kg N ha^(−1)),and conventional N(CN:240 kg N ha^(−1)).Compared to monocropping,relay cropping increased the stay-green traits of maize and soybean by 13%and 89%,respectively.Relay cropping prolonged the leaf stay-green duration in the maize and soybean lag phase by almost 4 and 8 days,respectively.Relay cropping maize(IM)increased the leaf area index(LAI)by 79.4%to 88.5%under NN and 55.5%to 148%under RN.Relay cropping soybean(IS)increased the LAI from 115%to 437%at days 40 to 50 after anthesis.IM increased yield by 65.6%.IS increased yield by 9.7%.HI and system yield were at their highest values under RN.In the relay cropping system,reduced N application extended green leaf duration,increased photosynthesis inside the canopy at multiple levels,ultimately increases soybean yield synergistically.

Effects of maize-soybean relay intercropping on crop nutrient uptake and soil bacterial community

Maize-soybean relay intercropping is an effective approach to improve the crop yield and nutrient use efficiency,which is widely practiced by farmers in southwest of China.To elucidate the characteristics of different planting patterns on crop nutrient uptake,soil chemical properties,and soil bacteria community in maize-soybean relay intercropping systems,we conducted a field experiment in 2015–2016 with single factor treatments,including monoculture maize(MM),monoculture soybean(MS),maize-soybean relay intercropping(IMS),and fallow(CK).The results showed that the N uptake of maize grain increased in IMS compared with MM.Compared with MS,the yield and uptake of N,P,and K of soybean grain were increased by 25.5,24.4,9.6,and 22.4%in IMS,respectively,while the N and K uptakes in soybean straw were decreased in IMS.The soil total nitrogen,available phosphorus,and soil organic matter contents were significantly higher in IMS than those of the corresponding monocultures and CK.Moreover,the soil protease,soil urease,and soil nitrate reductase activities in IMS were higher than those of the corresponding monocultures and CK.The phyla Proteobacteria,Acidobacteria,Chloroflexi,and Actinobacteria dominated in all treatments.Shannon’s index in IMS was higher than that of the corresponding monocultures and CK.The phylum Proteobacteria proportion was positively correlated with maize soil organic matter and soybean soil total nitrogen content,respectively.These results indicated that the belowground interactions increased the crop nutrient(N and P)uptake and soil bacterial community diversity,both of which contributed to improved soil nutrient management for legume-cereal relay intercropping systems.

Effects on Agronomic Traits,Yield and Benefit of One-year Triple Cropping "Maize-soybean" Strip Intercropping System Under Reduced Fertilizer Application

[Objectives] This study was conducted to investigate the effects on agronomic traits,yield and benefit of one-year triple cropping " maize-soybean" strip intercropping system under reduced fertilizer application. [Methods]A single factor randomized block design was used,and wide and narrow strip intercropping was adopted. Three different fertilization treatments,namely fertilizers for conventional field fertilization( A1),80% A1( A2) and 60% A1( A3) were applied to the field production. The fertilizing sites were about 25 cm away from maize and repeated three times. [Results]Compared with A1,the change laws of the agronomic traits and yield in the A2 and A3 intercropping systems were described as below. Agronomic traits: The plant height became shorter gradually for the spring soybean,but increased gradually for the summer soybean,the bottom pod height gradually reduced,and the node number,pods per plant and seeds per plant increased;and the plant height,ear length,rows per ear,seeds per row and 1 000-seed weight of the spring maize decreased. Yield: The yield of maize as the main crop decreased but not significant,by 3. 20% and 3. 99%,respectively in A2 and A3,both smaller than 5. 00%;the yield of the spring soybean significantly increased by 9. 70% and 11. 84%,respectively;the yield of the summer soybean increased by 5. 18% and 8. 98%,respectively;and the total yield increased by 0. 20% and 0. 92%,respectively. Benefit: The total output value increased by 2. 97 % and 4. 91 %,respectively,and the total benefit increased by 6. 39% and 11. 22%,respectively. [Conclusions] Under a 40% reduction in fertilizer applied in the field,the one-year triple cropping " maize-soybean" strip intercropping system still met the multi-target requirements of increasing grain production and economic benefits,and thus can be promoted and applied in Guangxi.

Relay-intercropping soybean with maize maintains soil fertility and increases nitrogen recovery efficiency by reducing nitrogen input

Optimized nitrogen(N)management can increase N-use efficiency in intercropping systems.Legume-nonlegume intercropping systems can reduce N input by exploiting biological N fixation by legumes.Measurement of N utilization can help in dissecting the mechanisms underlying N uptake and utilization in legume-nonlegume intercropping systems.An experiment was performed with three planting patterns:monoculture maize(MM),monoculture soybean(SS),and maize-soybean relay intercropping(IMS),and three N application levels:zero N(NN),reduced N(RN),and conventional N(CN)to investigate crop N uptake and utilization characteristics.N recovery efficiency and 15N recovery rate of crops were higher under RN than under CN,and those under RN were higher under intercropping than under the corresponding monocultures.Compared with MM,IMS showed a lower soil N-dependent rate(SNDR)in 2012.However,the SNDR of MM rapidly declined from 86.8%in 2012 to 49.4%in 2014,whereas that of IMS declined slowly from 75.4%in 2012 to 69.4%in 2014.The interspecific N competition rate(NCRms)was higher under RN than under CN,and increased yearly.Soybean nodule dry weight and nitrogenase activities were respectively 34.2%and 12.5%higher under intercropping than in monoculture at the beginning seed stage.The amount(Ndfa)and ratio(%Ndfa)of soybean N2 fixation were significantly greater under IS than under SS.In conclusion,N fertilizer was more efficiently used under RN than under CN;in particular,the relay intercropping system promoted N fertilizer utilization in comparison with the corresponding monocultures.An intercropping system helps to maintain soil fertility because interspecific N competition promotes biological N fixation by soybean by reducing N input.Thus,a maize-soybean relay intercropping system with reduced N application is sustainable and environmentally friendly.

Soil mineral nitrogen and yield-scaled soil N2O emissions lowered by reducing nitrogen application and intercropping with soybean for sweet maize production in southern China

The increasing demand for fresh sweet maize （Zea mays L. saccharata） in southern China has prioritized the need to find solutions to the environmental pollution caused by its continuous production and high inputs of chemical nitrogen fertilizers. A promising method for improving crop production and environmental conditions is to intercrop sweet maize with legumes. Here, a three-year field experiment was conducted to assess the influence of four different cropping systems （sole sweet maize （SS）, sole soybean （SB）, two rows sweet maize-three rows soybean （S2B3） intercropping, and two rows sweet maize-four rows soybean （S2B4） intercropping）, together with two rates of N fertilizer application （300 and 360 kg N ha-1） on grain yield, residual soil mineral N, and soil N2O emissions in southern China. Results showed that in most case, inter- cropping achieved yield advantages （total land equivalent ratio （TLER=0.87-1.25） was above one）. Moreover, intercropping resulted in 39.8% less soil mineral N than SS at the time of crop harvest, averaged over six seasons （spring and autumn in each of the three years of the field experiment）. Generally, intercropping and reduced-N application （300 kg N ha-1） produced lower cumulative soil N20 and yield-scaled soil N20 emissions than SS and conventionaI-N application （360 kg N ha-l）, respectively. $2B4 intercropping with reduced-N rate （300 kg N ha-~） showed the lowest cumulative soil N20 （mean value=0.61 kg ha-1） and yield-scaled soil N20 （mean value=0.04 kg t-1） emissions. Overall, intercropping with reduced-N rate maintained sweet maize production, while also reducing environmental impacts. The system of S2B4 intercropping with reduced-N rate may be the most sustainable and environmentally friendly cropping system.

Effects of Different Planting Pattern of Maize (<i>Zea mays</i>L.) and Soybean (<i>Glycine max</i>(L.) Merrill) Intercropping in Resource Consumption on Fodder Yield, and Silage Quality

An experiment was carried out at the field units of the north campus experimental areas in Northwest Agriculture and Forestry University, Yangling, Shaanxi Province, P. R. China. The experiment was conducted on summer season (June to September) to determine the effects of different planting patterns of maize and soybean intercropping in resource consumption on fodder yield and silage quality. The main treatments were one sole crop of maize (SM) and four maize-soybean intercropping patterns (1 row maize to 1 row soybean (1M1S), 1 row maize to 2 rows soybean (1M2S), 1 rows maize to 3 rows soybean (1M3S) and 2 rows maize to 1 row soybean (2M1S), respectively. The experiment was a randomized complete block design with three replications, and plot size of 12 m by 5 m. The crops were harvested when the maize reached at milk stage and soybean at R7 stage. The result indicated significant increase in fresh biomass and dry matter production of maize fodder alone as compared to maize intercropped with soybean fodder. It was correlated with a higher consumption of environmental resources, such as photosynthetically active radiation (PAR) and soil moisture by intercropping. After 45 days of ensiling period, silage samples were analyzed for pH, organic acids (Lactic, acetic, and butyric), dry matter (DM), crude protein (CP), ether extract (EE), neutral detergent fibre (NDF), acid detergent fibre (ADF), calcium (Ca), sodium (Na), phosphorus (P), magnesium (Mg), and potassium (K). It was concluded that in all intercropped silages, crude protein (CP) values were higher (1M1S, 12.1%;1M2S, 12.2%;1M3S, 12.4%;2M1S, 12.1%) than the monocrop maize (SM, 8.7%) silage. Higher organic acids (p < 0.05) were produced in the 1M3S silages as compared to others silages. The study indicated that among all intercropped silages, the 1M3S (1 row maize to 3 rows soybean) was preferable according to nutrient composition than other intercropped silages.