Potato Intercropping Research Articles

Utilization of agricultural climatic resources under the spring maize-spring potato intercropping pattern in Pengzhou city.

Utilization of agricultural climatic resources under the spring maize-spring potato intercropping pattern in Pengzhou city.

Cost-benefit analysis of an agroforestry innovation on karst land: replacing sweet potato by sealwort (Polygonatum cyrtonema) under plum trees in Chunfeng village, Sichuan province, China

ABSTRACTFor an ecological environment that is a “congenitally deficient” such as a rocky desertification area, it is particularly important to carry out adaptive response management. This paper addresses a case study on sealwort (Polygonatum cyrtonema) intercropping under plum trees (SIP) in China’s Chunfeng village. The system was developed in the framework of a land rehabilitation project, through a participatory process involving the villagers. We compare the performance of SIP to the previous management mode (sweet potato intercropping under plum trees: SPIP). Our results show that, although the establishment and operation costs of SIP are relatively important, the net present value of SIP is much higher than that of SPIP. SIP can also increase employment opportunities by, improve the welfare of vulnerable groups and is of some environmental value, especially protecting indigenous plant (sealwort) from overharvesting. However, the establishment and maintenance cost of SIP is huge, and long-term simulation results demonstrate a rather long pay-back period. We conclude in suggesting that similar adaptive management not only consider identifying alternative land-use through a participatory process, but also consider participants’ ability to pay, and market demand of the product.

Effect of Sweet Potato Vine Planting Orientation on the Growth and Yield of Sweet Potato/Maize Intercropping System in Makurdi, Southern Guinea Savanna, Nigeria

Two field experiments were carried out during the cropping seasons of 2016 and 2017 at the Teaching and Research Farm of the University of Agriculture, Makurdi, Benue State, Nigeria. The experiments sought to determine the effect of sweet potato vine orientation on growth and yield of sweet potato/maize intercropping system with a view to improve the productivity of maize/sweet potato intercropping in Makurdi. The experiment was a 2 x 2 x 3 split-split plot laid out in randomized complete block design with three replications. The main plot treatments were two cropping systems [sole cropping (sweet potato, maize), intercropping (sweet potato + maize)].The sub plot treatments were made up of two maize varieties (pop.66SR/ACR.91 SUWAH 1-SR and M2: pool18R/AK94DMRESR-Y). The sub-sub plot treatments comprised of three (3) sweet potato vine orientations (incline, loop and horizontal). The result obtained from the experiment showed sole cropping gave higher cob length, number of seeds per cob, cob weight, grain yield and 100-seed weight of maize than intercropping in both years. In all years, pool18R/AK94DMRESR-Y produced higher yield and yield parameters of maize than pop.66SR/ACR.91 SUWAH 1-SR irrespective of the cropping system. In 2016 and 2017, horizontal vine orientation gave higher vine length, root diameter, root length, number of saleable roots per hectare and weight of saleable roots than all the other vine orientations. Intercropping with pop.66SR/ACR.91 SUWAH 1-SR gave higher growth and yield parameters than intercropping with pool18R/AK94DMRESR-Y. All intercrop combinations had LER figures above 1.0 and LEC values above 0.25 in both years. CR values of sweet potato were consistently higher than those of maize in all intercrop combinations in 2016 and 2017

Crop rhizospheric microbial community structure and functional diversity as affected by maize and potato intercropping

ABSTRACTField trials were conducted to evaluate the effects of different cropping patterns (maize monocropping, maize and potato intercropping, potato monocropping) on microbial abundance, community structure, and microbial functional diversity using plate culture and Biolog technique. Results showed that compared with monocropping, intercropping increased the abundance of soil bacteria, fungi, and actinomyces in rhizosphere surrounding maize and potato. The average well color development (AWCD) and Shannon index (H) were higher in intercropping soil than that found in monocropping soil. The ability of rhizospheric soil microorganisms in utilizing six types of carbon sources had definite differences, and the most dominant community structure was the carbohydrates metabolic groups. Principal component analysis demonstrated that intercropping changed significantly soil microbial community functional diversity depending mainly on carbohydrates and carboxylic acids. Our findings suggested that maize–potato intercropping has positive effects on the improvement of soil microbial abundances, activity, and functional diversity.

Contribution of nutrient uptake and utilization on yield advantage in maize and potato intercropping under different nitrogen application rates

Intercropping of maize and potato, as an important intercropping planting pattern, has a prominent advantage of resource utilization and yield. However, contribution of nutrient uptake and utilization to crop yield advantage and its response to N application rates remain unclear. Through a 2-year plot experiment, including maize monoculture, potato monoculture and maize intercropping with potato at 4 N-fertilized levels of N0(0 kg·hm-2), N1(125 kg·hm-2), N2(250 kg·hm-2) and N3(375 kg·hm-2), nutritional contribution of yield advantage of intercropping was studied. The results showed that weighted average uptake of nitrogen, phosphorus and potassium was gradually increased with N application rate in monocultures, but increase followed by a decrease in intercropping. Compared with monoculture at the same N level, nutrient uptake advantage of intercropping was the highest at N1, which increased nitrogen, phosphorus and potassium uptake by 14.9%, 38.6% and 27.8%, respectively. However, the nutrient use efficiencies were highest in intercropping at N0 and N3 with increment of 3.5%-14.3% for nitrogen, 3.5%-18.5% for phosphorus and 10.6%-31.6% for potassium. Maize and potato intercropping had a significant yield advantage at N0 and N1. Yield advantage in intercropping attributed to improvement of nutrient use efficiency at N0 while to increase of nutrient uptake at N1. To utilize the yield advantage from nutrient uptake, controlling input of nitrogen fertilizer is necessary in intercropping.

Maize and Potato Intercropping: A Technology to Increase Productivity and Profitability in Tigray

Abstract Smallholders have limited landholding in the highlands of Tigray and therefore there is a critical need to improve land use efficiency (LUE). One way to improve the LUE is through intercropping of companion crops including maize and potato. An experiment was conducted to evaluate the intercropping ratio as a means to improve land use efficiency during the 2012 cropping season. The treatments tested were three intercropping ratios of maize: potato in 1:1, 1:2, 2:1 row arrangement compared against the maize and potato only cropping. The objective of the study was to identify the best intercropping ratio that maximizes land use efficiency. Land equivalent ratio (LER) was used to compare the land use efficiency of the intercrops with each sole crop. The total yield of intercropped crops were greater than sole cropping, shown by LER>1. The overall advantage of intercropping ranged from 35 to 58%. The highest land equivalent value of 58% was recorded for one maize and two potato rows arrangements indicated a yield advantage of 58% over sole crop. The partial land equivalent value of both crops in intercropping was less than one indicating the cohesiveness of both crops in intercropping. Thus, it can be concluded that 1maize: 2 potato intercropping is a viable agronomic option in increasing land use efficiency and increased food security. It is, therefore, imperative to demonstrate the best treatment under farmer’s condition.

Successive Intercropping of Potato and Mungbean with Sugarcane

The experiment was carried out at the Bangladesh Sugarcane Research Institute (BSRI) farm at Ishurdi, Pabna, Bangladesh during2008-2009 and 2009-2010to investigate the growth and yield of main crop sugarcane, and companion crops potato and mungbean as successive intercrops. Row to row spacing (RRS) of sugarcane were 80 (S1), 100 (S2) and 120 cm (S3) and sugarcane was intercropped with 1, 2 and 3 rows of potato as 1st intercrop and followed by mungbean with same row ratio as 2nd intercrop. Sugarcane and companion crops potato and mungbean were cultivated following the cultivation methods of BSRI and Bangladesh Agricultural Research Institute (BARI), respectively. To provide more light to intercrops bended leaves of sugarcane on both sides of rows were cut at middle and compared with non-cutting of leaves in respect of growth and yield of main crop and intercrops as well. The total dry matter production, cane yield and sugar yield were the highest at 120 cm RRS of sugarcane (non-leaf cutting=C0) intercropped with 3 rows of potato followed by 3 rows of mungbean (S3C0). The number of tiller and millable canes, and leaf area index (LAI) were the highest at 80 cm RRS of sugarcane (C0) with one row of potato and one row of mungbean (S1C0). The effect of light interception on growth and yield of first intercrop (potato) was insignificant whereas it was significant for second intercrop. Yield of mungbean (2nd intercrop) and light interception ratio (%) was the lowest in S3C1 where sugarcane RRS was 120 cm + 3 R potato followed by 3 R mungbean with leaf cutting (LC). The results of the experiment indicated that sugarcane transplanted at RRS of 120 cm with 3 rows of potato followed by 3 rows of mungbean can be grown as intercrops for increased yield of sugarcane as well as for increased cropping intensity and might be recommended for farmers practice in High Ganges River Flood Plain soils under AEZ 11 of Bangladesh. The Agriculturists 2016; 14(2) 67-76

Contribution of interspecific interactions and phosphorus application to increasing soil phosphorus availability in relay intercropping systems

Maize-based intercropping, especially with legumes, can result in increased yields of the whole cropping system and lead to efficient utilization of soil phosphorus (P). Field experiments were conducted for two consecutive years to investigate the mechanisms behind the increased yields of maize by increasing soil P availability in intercropping systems and how P application and companion crops influenced the process. The planting patterns and P fertilizer application rates significantly affected P taken up by maize. The increased yields of maize − average increases of 22.67 and 12.60% for maize (Zea mays)/soybean (Glycine max) and maize/sweet potato (Dioscorea esculenta)intercropping, respectively; and 12.60 and 7.17% for maize/soybean and maize/sweet potato after P fertilization, respectively − indicated that the interspecific stimulation of P uptake may be a general phenomenon controlled by soil P availability and crop species. Under the maize/soybean intercropping system, considerable facilitation was observed when roots were not kept separate; suggesting that selective enrichment of competent species may be responsible for increased P uptake during intercropping. Positive interactions were supported by soil P activation processes that increased P availability, such as pH changes and acid phosphatase activity. In the intercropping of maize/soybean, acid phosphatase activity was significantly higher than that of maize/sweet potato. In accordance, soil acidification increased with root interaction. Soil acidification increased in maize/soybean intercropping with root contact as did acid phosphatase activity especially in P-deficient soil, which enhanced soil P availability. It was concluded that there was indeed P activation when maize grew with root interactions in the maize/soybean and maize/sweet potato systems. However, the facilitation was stronger in P-deficient soil. Interspecific interactions and P application together contributed to the yield advantage of intercropping.

Development of Sugarcane-cum-Potato Planter for Mechanisation of Simultaneous Planting of Sugarcane and Potato

Sugarcane and potato are the two major cash crops cultivated in the Indo-Gangetic plains of South Asia. Growing potato as intercrop with sugarcane has a synergistic effect on sugarcane, resulting in increased economic returns to farmers. In order to mechanise simultaneous planting of sugarcane and potato for intercropping, a new planting machinery named as sugarcane-cum-potato planter was designed and developed at ICAR-Indian Institute of Sugarcane Research, Lucknow, India. It was equipped with furrowers for opening of furrow and ridge making in between furrows, sett cutting unit for cane planting, potato seed tuber metering mechanism for potato planting, covering unit to cover planted sugarcane setts and potato and insecticide application unit. The designed equipment planted two rows of sugarcane in furrows and two rows of potato on ridges simultaneously in single pass. Picking and dropping of seed potato were automatic, whereas sugarcane seed stalk feeding for sett cutting was manual. Field testing of the developed planter was conducted at IISR farm in sandy loam soil. The effective field capacity of planter was 0.127 ha h−1. Average soil cover on sugarcane setts was 45 mm. Average depth of seed potato tuber placement on the ridges was 40 mm, and average tuber to tuber spacing was 192 mm. Developed machine-planted sugarcane at furrow spacing of 750 mm with average overlapping of 68 mm between the setts. The cost of planting operation with developed equipment was rupees 3160 ha−1 as against rupees 13,600 ha−1 in conventional planting. Saving in cost of planting operation was about 76% and labour about 90% with the developed planter as compared to conventional planting. Irrigation water use efficiency, yield attributes and total yield increased significantly in potato–sugarcane intercropping as compared to relay cropping of potato and sugarcane. Benefit/cost ratio in mechanised intercropping of potato and sugarcane with the developed planter was 2.57:1 followed by conventional manual intercropping (2.26:1) and manual potato–sugarcane relay cropping (1.84:1).

Effect of Different Nitrogen Rates on the Nitrification Potential and Abundance of Ammonia-oxidizer in Intercropping Maize Soils

The objectives of this study were to explore the effects of different nitrogen rates on the nitrification potential in intercropping maize soils. The experiment included two plantation types (maize monocropping and intercropping maize and potato) and four nitrogen levels (N0: no fertilizer treatment, N1: 1/2 conventional fertilizer treatment, N2: conventional fertilizer treatment, N3: 3/2 conventional fertilizer treatment). Abundance of AOA and AOB was analyzed with real-time quantitative PCR (Q-PCR) and soil properties were also measured. Results of this study suggested that the PNF of soils, the abundance of AOA and AOB were increased with increasing N fertilization in conventional fertilizer range, and there was no significant difference between N2 and N3 treatments. The influences of intercropping on PNF, AOA and AOB were associated with N application rates and crop growth period, as well as the benefits of ammonia oxidizer and nitrification of intercropping on N1 level. Fertilization was obviously the main driving force of the PNF, correlation analysis indicated that water content was the main environmental factor affecting the nitrification potential. Nitrification potential in maize and potato intercropping soils exhibited significant positive correlations with AOA and AOB amoA gene abundance. Maize and potato intercropping could decrease the abundance of AOA and AOB, but it resulted in dominance of AOB among nitrification bacteria in these soils. In conclusion, N fertilizer and intercropping could affect both soil nitrogen internal cycling process and the abundance of AOA and AOB, which further affected soil environmental quality.

Growth dynamics and nutrient content of winter maize(Zea maysL.)-based intercropping systems in relation to integrated nitrogen management under Indo-Gangetic plains of Uttar Pradesh

Afield experiment was carried out for two consecutive winter (rabi) seasons of2013-14 and 2014–15 at Kanpur, India to find out the effect of integrated nitrogen management (INM) on growth dynamics and nutrient content of winter maize (Zea mays L.) intercropped with potato (Solanum tuberosum L.), Indian mustard [Brassicajuncea (L.) Czernj. & Cosson] and linseed (Linum usitatissimum L.) for Indo-Gangetic plains of Uttar Pradesh. The experiment consisted of three intercropping systems (maize + potato, maize + mustard and maize + linseed grown in 3: 1 row ratio) and three INM practices, viz. 100% recommended dose of nitrogen (100% RDN), 75% RDN through inorganics + 25% RDN through organics (75 + 25% RDN), and 50% RDN through inorganics + 50% RDN through organics (50 + 50% RDN) along with sole cropping of maize, potato, mustard and linseed. Results revealed that dry matter accumulation increased progressively due to each crop growth stage. Maize + potato (3: 1) intercropping system resulted in the highest dry matter accumulation plant−1 throughout the crop growth, followed by maize + linseed (3: 1). Amongst different INM practices, treatment with 75 + 25% RDN revealed the maximum dry matter accumulation plant−1 and plant height. Maize + potato intercropping system exhibited higher absolute growth rate (AGR) and crop growth rate (CGR) during all the stages of crop growth, followed by maize + linseed system. Maize + potato also recorded higher relative growth rate (RGR) throughout the crop growth, except between 90 to 120 days after sowing (DAS). Maize+mustard intercropping system recorded lesser values of AGR, CGR and RGR throughout the crop period. INM practices improved the AGR and CGR but RGR was improved during later growth stages (120 days onwards) only. Application of 75 + 25% RDN recorded higher values of AGR and CGR. This treatment (75 + 25% RDN) also improved the RGR up to 90 DAS but between 90 to 120 DAS application of 75 + 25% RDN lowered RGR as compared to 100% RDN; however RGR further improved during later growth stages (120 days onwards) due to application of 75 + 25% RDN. Application of 50 + 50% RDN recorded minimum values of these growth indices. Correlation studies indicated significant positive correlation of seed yield with DMA, AGR, CGR and RGR as well as combinations of most of the growth stages, except RGR 90–120 DAS, emphasizing the importance of higher growth rate during grand growth period for best yield accrual in winter maize.

Increase in yield of winter maize + potato intercropping system by weed management

Increase in yield of winter maize + potato intercropping system by weed management

Effects of intercropping of maize and potato on sloping land on the water balance and surface runoff

It has been suggested that the increased yields of intercropping are strongly correlated to its effect on controlling water loss. However, studies of the effect of intercropping on controlling water loss on sloping land are few. In this study, with maize (Zea mays L.) and potato (Solanum tuberosum L.) as experimental crops, a comparison was made of surface runoff, soil evaporation, soil moisture content, crop transpiration and crop yield between the intercropping and the sole crop on sloping land during 2012–2013. Data showed that: (1) the accumulative runoff in maize and potato intercropping (IC) was not significantly different from that in sole potato (SP), but significantly decreased by 56.75–74.53% (P<0.05) as compared with that in the sole maize (SM); (2) the daily mean soil evaporation in IC decreased by 20.83–28.44% (P<0.05) as compared with that in SM, and decreased by 6.99–14.85% (P=0.034 in 2012 and P=0.064 in 2013) as compared with that in SP; (3) the soil moisture content in IC at each observation period was higher than that in SM and SP (P=0.101 in late July and P<0.05 in other periods); (4) the transpiration in IC was significantly higher than that in SM and SP (P<0.05); and (5) the land equivalent ratio (LER) of IC was 1.19–1.34 (P<0.05), indicating that the maize and potato intercropping induced a yield advantage. Overall, the results suggested that on sloping land, the maize and potato intercropping can reduce the water loss from the surface runoff and the soil evaporation, thus increasing the soil moisture content and contribute to the increase of the transpiration and crop yield. Data also indicated that the lower runoff in maize and potato intercropping compared with sole maize is associated not only with the higher leaf area index, but also with the potato tubers.

Productivity and economics of mixed intercropping of potato with other short duration vegetables

Mixed cropping has proven to be a useful approach to maximizing the crop productivity. Now a day, poverty alleviation of resource poor farmers is an important issue in Bangladesh and hence, mixed cropping system can be helpful to food security as well as to reduce poverty. The experiment was carried out at Moulvibazar and Sylhet districts during 2011-12 and 2012-13 to find out the agronomic performance of mixed intercropping of potato with different short duration vegetables crop and to increase the cropping intensity and profitability of the farmers in Sylhet region. The trial was conducted following RCB design with six dispersed replications. There were five treatments: T1: sole potato (100%), T2: potato (100%) + bush bean (50%), T3: potato (100%) + garden pea (50%), T4: potato (100%) + radish (50%) and T5: potato (100%) + bush bean (25%) + garden pea (15%) + radish (10%) used in the trial. Results revealed that the highest equivalent yields of potato 37.09 and 35.37 t ha-1 were recorded in potato (100%) + radish (50%) mixed intercropping system from Moulvibazar and Sylhet, respectively. Cost benefit analysis also showed that highest gross returns Tk. 3,70,910 and 3,53,690 and net returns Tk. 2,65,710 and 2,48,490 and benefic benefit cost ratio 3.53 and 3.36 were recorded in the same treatment combination in both locations, respectively. So, 100% potato with 50% radish intercropping system may be recommended as profitable mixed intercropping system in Sylhet region.Bangladesh Agron. J. 2014, 17(2): 39-46

Effects of Row Intercropping System of Corn and Potato and Row Spacing of Corn on the Growth and Yields of Atlantic Potato Cultivar Planted in Medium Altitude

Abstract: The objective of this research was to study the growth and yield of Atlantic Potato cultivar grown in medium altitude under corn and potato intercropping system and corn row spacing. The experiment was conducted in a research station of Agriculture Faculty of Padjajaran University located in Jatinangor at the altitude of 685 m above sea level with C3 rainfall in Inseptisol soil. It was laid out in Split Plot Design consisting of two factors and four replications. Manipulating growing environment by using corns as shades under different cropping systems was created as the main plot factor which consisted of two cropping systems: 1:1 corn+potato arrangement (one row of corns, one row of potatoes) and 1:2 corn+potato arrangement (one row of corns, two rows of potatoes). The row spacing of corn planted within the rows as the subplots were at 30, 40 and 50 cm. Results of the research indicated that there were no interactions between the corn and potato cropping system and the corn row spacing system over their growth, yields and Land Equivalent Ratio (LER). The plants height of potatoes and their leaf area under 1:1 arrangement were larger compared to those under 1:2 arrangement. On the other hand, the dry mass and the chlorophyll concentrations showed lower value. Although they yield the equal crops, the weight per plot, the yields per hectare and the LER value of 1:1 corns+potatoes cropping system showed higher result. While the row spacing system of corn at 50 cm showed higher value of dry weight, yield per plant, weight per plot and yield per hectare, yet it showed lower value of LER.

Hybrid maize and sweet potato intercropping: a technology to increase productivity and profitability for poor hill farmers in Bangladesh

The experiment was conducted at the Hill Agricultural Research Station, Khagrachari during two winter seasons of 2010-11 and 2011-12 to find out suitable planting system of the component crops for increasing productivity and profitibility for hill farmers of Bangladesh. Three intercrop combinations viz., (i) maize paired row + 2 rows sweet potato, (ii) maize normal row +1 row sweet potato and (iii) sweet potato normal row + 1 row maize were evaluated against their respective sole crops. In all combinations, light availability was more at early growth stage and reduced gradually with the advancement of canopy development of maize. Light availability was minimum at 100 days after emergence and thereafter slightly increased in three intercrop combinations. Among intercrop combinations, light availability to sweet potato canopy was more in maize paired row + 2 rows sweet potato combination through out the crop period which enhance tuber formation, tuber bulging and tuber yield. Contrary, sweet potato vines provide a mulch cover for maize which preserve soil moisture and reduce weed infestation producing higher yield and yield components of maize. Maize yield (cob yield: 19.82 t ha-1, grain yield: 8.98 t ha-1), tuber yield of sweet potato (17.11 t ha-1) and maize equivalent yield (cob equivalent yield: 42.63 t ha-1, grain equivalent yield: 15.82 t ha-1) were the highest in maize paired row + 2 rows sweet potato combination. Similarly, the highest gross return (for cob: Tk. 1,27,890 ha-1, for grain: Tk. 1,58,200 ha-1), gross margin (for cob: Tk. 87,890 ha-1, for grain: Tk.1,08,200 ha-1) and benefit cost ratio (for cob: 3.20, for grain: 3.16) were also obtained from the same combination. The results revealed that maize paired row + 2 rows sweet DOI: http://dx.doi.org/10.3329/sja.v12i2.21922 SAARC J. Agri., 12(2): 101-111 (2014)

Determination of Effective Spatial Arrangement for Intercropping of Maize (Zea mays L.) and Potato (Solanum tuberosum L.) Using Competition Indices Ethiopia

An experiment was conducted on the determination of effective spatial arrangement for intercropping of maize and potato using competition indices at South Wollo, Ethiopia for two consecutive years, 2010-2011. The objective of the study was to determine effective spatial arrangement for intercropping of maize and potato. The treatments were 1 maize:1 potato, 2 maize:2 potato, 1 maize:2 potato (a), 2 maize:1 potato (a), 1 maize:2 potato (b) and 2 maize:1 potato (b). Sole maize and sole potato was used for comparison. JMP 5 (SAS) software’s were used to compute the analysis of variance. The combined yield advantages in terms of total land equivalent ratio (LER) and Income equivalent ratio (IER) indices were greatest in the cases of 1 maize:1 potato followed by 1 maize:2 potato (b) intercropping arrangement. Area time equivalent ratio (ATER) values showed an advantage of 75.0% only in 1 maize:1 potato. Effective Monetary advantage (EMAI) index was highest in 1 maize:2 potato (b)followed by 1 maize: 1 potato intercropping arraignments. However, Competitive ratio (CR) values for all crops in all intercropping arrangements were less than one indicating both crops are equally competitive. Based on the this findings, 1 maize: 1 potato followed by 1 maize:2 potato (b) intercropping arrangement gave the highest PRY, LER,ATER, IER and EMAI; and lowest CR value and in turn achieve higher productivity rates of the two crops, which lead to favorably recommend the use and utilization of this system in south wollo. It is recommended that this project was conducted for two years, there was lack of budget and hence this research should be repeated in different agro ecology and spatial arrangement.

Effects of Nitrogen Application Rates on Rhizosphere Microbial Community Functional Diversity in Maize and Potato Intercropping

Field trials were carried out to investigate the effects of different nitrogen application rates N0(0 kg·hm-2), N1(125 kg·hm-2), N2(250 kg·hm-2)and N3(375 kg·hm-2)on the rhizosphere microbial population and metabolic function diversity of maize and potato under intercropping using plate culture method and BIOLOG technique. The results indicated that nitrogen(N1, N2 and N3) application in-creased the amounts of bacteria, actinomyces and total microbes, but decreased the quantities of fungi significantly in rhizosphere soil of maize and potato in intercropping, and the highest increment was with N2 treatment. In comparison with N0, nitrogen fertilizer application could increase significantly the diversities of soil microbial community, the utilization rate of carbon source, richness of soil microbial community. And the AWCD value, Shannon-Wiener index(H), Simpson index(D), Evenness index(E)and Richness index(S)in rhizosphere soil of maize under intercropping were the highest at N3 treatment, while that of potato were the highest at N2 treatment, but the effects of different N application rates on the ability of rhizospheric microbes in utilizing six types of carbon sources were different. Principal component analysis(PCA)and cluster analysis showed that there were differences in carbon substrate utilization patterns and metabolic characteristics of the soil microbes in maize and potato intercropping with different N application rates. It suggested that applying N could regulate the rhizosphere soil microbial communities and promote the functional diversity of crop intercropping.

Effects of Maize and Potato Intercropping on Rhizosphere Microbial Community Structure and Diversity

Effects of Maize and Potato Intercropping on Rhizosphere Microbial Community Structure and Diversity

Effects of slope position, aspect and cropping system on soil nutrient variability in hilly areas

Human activities and topography are main factors affecting soil nutrient variation. However, the relationships between these factors are both site- and scale-specific. In hilly areas of south-western China, the dominant cropping systems are rice, vegetables, oranges, Chinese red pepper and maize–sweet potato intercropping. In the present study, slope position (valley, low slope, flat slope, middle slope, upper slope, ridge) and aspect (north, east, south, west) were derived to investigate the relationships among cropping system, terrain, and soil nutrients at county scale. Crops were mainly planted at middle or flat slope positions. Rice and orange plants were evenly distributed across the aspects whereas vegetables were mostly planted on the northern aspect. Red pepper and maize–sweet potato plants were mainly grown on the western and southern aspects. Rice sites had higher contents of organic matter and available nitrogen (N) and lower contents of available phosphorus (P) and available potassium (K). For dryland cropping systems, vegetable sites had higher contents of organic matter, available N, and available P. Red pepper sites had higher contents of available K. Contents of organic matter and available N were generally higher at lower landscape positions. Contents of available K were higher at lower and flat slope positions. Contents of available P were higher at higher landscape positions. Contents of organic matter and available N were higher on the northern and eastern, and lower on the western aspects. Contents of available P were higher on the western and lower on the northern aspects. No significant differences were found for available K across the aspects. Classification tree algorithms indicated that relative importance of the variables on soil nutrient variation was in the order: (i) cropping system, (ii) slope position, and (iii) aspect.