Benhui WEI,Zhangyou SHEN

Cash Crops Research Institute,Guangxi Academy of Agricultural Science,Nanning 530007,China

Chinese yam (Dioscorea opposita Thunb.)in Dioscorea L.of Dioscoreaceae is an annual or perennial vine[1-2],which is widely distributed in hill and mountainous areas in northeast of China,north China,centralChina,and southeastand southwest of China,and Guangxi is one of main producing areas of Chinese yam in China[3-4].Chinese yam has wide application,and is a kind of effective economic crop serving as food,vegetable and medicine,which had good market prospect and developing potential,and is cultivated and popularized worldwide due to its highquality starch and special nutrients as well as food therapy components[5-6].In recent years,Chinese yam has developed rapidly in China,with a planting area above 46.69×104hm2in whole China,and become one of main crops which increases farmers’income in main producing areas of Chinese yam in China[7].

World population has reached 7 billion,imbalance between food supply and demand would be more obvious,food crisis would be severer,and the problem of food safety thus would become a longer-term issue facing the world[8].In China,with population growing year by year,the agricultural acreage is reducing continuously,and has reached the red line of 1.206×108hm2,and furthermore,farmers are not enthused in planting crops,so that the problem of food safety would be more acute.Under this situation,in the development strategy of food problem,China puts moreemphasis on the effective improvement of yields per unit area in main food crops including rice,corn and wheat,and also pays attentions to some traditional minor crops,aiming atincreasing food sources greatly by developing minor crops and ensuring total food supply.The writer of this paper deemed that this strategy could yet be regarded as one of the important measures for maintaining and ensuring national food safety of China.

However,Fortraditional cultivation of Chinese yam,it is necessary to dig a deep trench during sowing and harvest,which islabor and timewasting,seriously affecting the industrial development of this crop[9].According to the researches of the writer over the years,especially for the National Scientific and Technological Special Program,“Techniques and Research on Effective Cultivation of Chinese Yam”,efficient cultivation techniques including directional tuberization,Fenlong(furrowing)and continuous cropping tolerance were developed,playing an active role in promoting the development of Chinese yam in China.In order to broaden the planting range of Chinese yam and adapt the facts of increasing population and reducing cultivated land resource,this study developed a Chinese yam no-tillage ecological cultivation technique.

Technique Principle and Characteristics

By use of partial measures in the“directional tuberization cultivation method”invented by the writer,the Chinese yamno-tillage ecological cultivation technique adopted no-tillage by arranging a material to be bagged for Chinese yam planting and tuberization at intervals in barren hills and sloping field,low-production dry land,forest land and other non-staple food land withoutaffecting ground ecological environment,allowing Chinese yam to complete growth and development under the environmentenabling high yield and good commodity and to grew freely without the need of putting up shelves for stems,achieving the effects of forming ecological environment with biodiversity and reducing usage offarm chemicals.Such method could further broaden Chinese yam planting and production in noncultivated land and increase farmers’income and good source.

Methods and Techniques

Selection of planting site

Low-production dry land,as well as non-staple food land includingbarren hills and sloping fieldand forest land suitable for cultivating Chinese yam could be selected.

Planting structure

On the land described in“Selection of planting site”,planting was carried out according to the depth of tuberization groove of 1.0-1.2 m,a plant spacing of 0.5-0.6 m and a row spacing of 2.0-2.5 m at a density of 4 500-47 500 plants/hm2.

Planting groove

Grooving was performed manually or with a small machine.The top end of the shovel of the machine was semicircular with a diameter of 12-13 cm.During grooving,the shovel cut soil from top to bottom,forming a groove with a depth of an upper part of 12-15 cm and a depth of a lower part of 16-20 cm and semi-circular smooth bottom.The whole groove was angled with the horizontal plane by 10°-30°to facilitate smooth elongation during tuberization of Chinese yam,to thereby improve the commodity of Chinese yam.

Preparation of materialto be bagged for planting

The material to be bagged for planting was prepared by mixing local soil,river (trench)sand,an organic fertilizer and a compound fertilizer,among which the ratio of local soil to river(trench)sand was 2∶1,the amount of the organic fertilizer was 1 000 g per bag and the amount of the organic fertilizer was 150-200 g per bag.

Treatment of planting bag

A thickened plastic film was adopted and tailored according to a length of 1.2-1.4 m and a width of 0.45-0.50 m.

Laying of material to be bagged and seeding

Tailored plastic was laid in each planting groove at first,the prepared material to be bagged was placed on the plastic,the plastic at two sides was rolled backward and pressed with soil to form a cylinder shape,and the two upper corners of the plastic filled with the bagged material were turned over to form a horn mouth;seeds were placed in the horn mouth and covered with soil with a thickness of 5-7 cm;and finally,the soil at the two sides of seeds was subjected to deep digging with a depth of about 20 cm,and applied with about 100 g of a compound fertilizer(deep digging and fertilization at two sides could function to store water and supply fertilizer).

Management

In principle,Chinese yam grew naturally without more manual intervention.However,it was necessary to observe seedlings and fill the gaps with seedlings,to thereby ensure tidy and strong seedlings.

Harvest

Harvest was conducted according to different regions,maturities of different varieties and market requirement.During harvest,the tubers were taken out carefully.

Application Range of Notillage Ecological Cultivation Technique for Chinese Yam

Basic ecoregion range

According to the experiments and observation over the years,the yam directional tuberization technique was more successful in the regions south of the Yangtze River,and therefore,the technique of this study might be feasible in this range.Other regions also could be experimented.

Cultivated Cropland

Without affecting the planting area of other staple food grain,cropland or dry land with good drainage conditions could be used for planting yam.

Barrenhills and sloping field

Barren hills and sloping field having certain slopes generally could be used advantageous,achieving the effects of increasing food sources,reducing water and soil loss as well as improving ecological quality of vegetation.

Forest land

Mountainous regions with young forests or open forests could be utilized for planting at a low density.

Utilization of nested soil on rocky mountains

Places might be found for planting grooves and material bags by utilizing nested soil on rocky mountains according to local conditions.This technique allows the stems and leaves of Chinese yam to climb naked stones on the spot,achieving the effect of improving stony desertification in rocky mountain areas.

Conclusions

This paper expounded the principle and characteristics of Chinese yam no-tillage technique in detail,and explained the process of the Chinese yam no-tillage ecological cultivation method and technique.The no-tillage ecologicalcultivation technique for Chinese yam as one of the crops with the brightest prospects of development has the advantages of simple operation,low cost and wide application range,and could increase sources of food and raw materials for agro-product processing as well as improving ecological environment efficiency of planting regions,worthy of concerning.

According to the result of this study,the bred varieties of Guihuai series had a single-plant yam weight of 2-3 kg,and up to 4-5 kg in the case of high yield by applying the technique of this study.For barrenhills and sloping field,the yield was 12 000-22 500 kg per hectare at the density of 4 500-7 500 plants/hm2.This study provides a new approach for increasing farmers’income.

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