Technical Standards for Lotus Root-Redswamp Crayfish Integrated Farming

Xuejin ZHOU, Jiahong ZHANG, Guangming HAN, Xiangming KOU, Shouhong WANG, Jianhua BI, Lingyu ZHU, Rong XU, Guiliang WANG

1.Agriculture Committee of Yangzhou, Yangzhou 225001, China;

2. Eco-aricultural Engineering & Technology Research Center of Jiangsu Province, Yangzhou 225009, China;

3. Institute of Agricultural Sciences of Lixiahe District in Jiangsu Province, Yangzhou 225007, China

Lotus root-redswamp crayfish integrated farming is the ecological-grow mode with planting and aquaculture mutual benefited. It has been popularized in the Lixiahe District,Jiangsu Province,where there is abundant water,in large area,and it is of great significance to promote the growth of agricultural efficiency and increase of farmers’ income. The water level in the lotus root field is shallower than that in the pond but deeper than that of paddy field,making it qualified for the requirements on water requirements of redswamp crayfish.Redswamp crayfish has short growth cycle and fast growth speed,and it only takes about 2 months for the juvenile crayfish to grow into adult prawn[1].In May and June,when the redswamp crayfish grows fast and the fertilizing amount of the lotus field is large, the lotus leaves provide excellent shading environment for the growth of redswamp crayfish, and various planktons provide high quality fish baits for the young crayfishes. After the middle June,with the water quality becoming clean, the number of benthonic animals like chironomidae larvae grows, which can provide enough animal baits for redswamp crayfish[2].Using food chain technology, lotus root-redswamp crayfish integrated farming mode can produce pollutionfree lotus root and redswamp crayfish,which improves the safety qualification for agricultural product, enhances the market competitiveness of agricultural products and leead the farmers to getting rich.

To standardize the lotus rootredswamp crayfish integrated production technique, based on years of research and experimental extension,the production technical specification for the integrated farming of lotus rootredswamp crayfish is formulated, and it has already set many demonstration and spreading bases in many areas,which have achieved good social, economic and ecological benefits, promoting the development of the aquatic animals and plants specialized economy along the lakes, rivers and ports of Jiangsu Province.

Producing Environmental Conditions

The producing environment for the integrated farming of lotus rootredswamp crayfish should be in accordance to the requirements of GB 18407.1-2001 and NY 5361-2010.The lotus field to raise redswamp crayfish should have adequate water sources,convenient irrigation and drainage,good water quality, no living and industrial pollution, strong water retention ability, soil pH value of 6.5-8.5,and it should be suitable for the breeding of planktons.

Variety Selection

Lotus

The most appropriate varieties should be the edible lotus varieties which are fit for the cultivation in Lixiahe Region in Jiangsu Province like Dazihong, Yangou No.1, Elian No.1,Elian No.2,Elian No.4.

Redswamp crayfish

It should select the redswamp crayfish seedlings with regular size after artificial breeding, which are native to the environment of Lixiahe region.

Farmland Works

Excavation of redswamp crayfish ditch

Circular grooves with the width of 1.5-2.0 m and depth of 0.5-0.7 m should be dug around the lotus field,and in the center of the field, cross shaped or “#” shaped grooves with the width of 0.6-0.8 m and depth of 0.5-0.7 m, which are connected with the grooves around the field. The inlet and outlet are set at the opposite corners of the lotus field.The water inlet is set at the field ridge,and the water outlet is set at the bottom of the groove,which should be sealed with the 60-mesh stainless steel meshes to prevent the harmful organisms from entering and redswamp crayfish from fleeing.

Field management

Fertilization Every 2 to 3 months,1 500- 3 000 kg of decomposed manure or 100-150 kg of decomposed cake fertilizer per mu can be applied to the lotus planting area. Enough base fertilizer is applied for the first time application, and after fertilization,the soil should be deeply ploughed for 20-30 cm.

Land preparation The water field for lotus cultivation should be fully ploughed and harrowed to make the field ridge firm enough (field ridge is over 50 cm higher than the field surface with the width over 1.5 m), field flat, groove clean (there is not too much sludge, and the thickness of sludge should be no more than 20 cm). Before planting, 1-3 cm of shallow water layer should be kept.

Lotus field disinfection

At 10-15 d before stocking young redswamp crayfish, disinfecting drugs like calcined lime, bleaching power shall be timely used to disinfect the grooves. The drugs should be applied according to the specification of NY 5071-2002.

Aquatic plant planting and snail putting

Aquatic plants like Hydrilla varticillata, Iraq nuttallii, Vallisneria spiralis should be planted in the circular grooves and center groove, and the aquatic plants planting area should account for 2/3 of the total groove area.The field water body contains duckweed. And 20-30 kg of snails per mu of water body are put into the grooves.

Settings of flee prevention facilities

The consolidated field ridge should be 40-50 cm higher than the water surface,and rigid plastics should be buried 20 cm deep into the soil around the ridge,and 50 cm above the soil is enough.Every 1-2 cm,bamboo chip or timber pile is used to fix the outside plastic film. Ground bamboo cage or other shrimping tools need to be set at the water inlet and outlet for long-term use. It should timely check whether there is crayfish fleeing away.

Lotus Root Planting

Lotus root planting requirements

The lotus root to be used as the breeding lotus root should have thick back knob, smooth surface, ripe enough, 2 complete terminal buds,complete lateral bud and leafbud, no disease and injury and unit weight of about 750 g.

Lotus root cultivation

Cultivation time In general, the lotus root is cultivated in late April to mid May.

Cultivation density About 6 000-7 500 plants of breeding lotus roots are planted per hectare, and the total planting amount is about 4 500-6 000 kg/m2.

Cultivation method Before lotus root planting, inclined shallow pits with the depth of 12-15 cm are dug, and oblique interpolation method is used to put the lotus root into the soil with the end slightly upward and front and back tilting angel of 20-25 degree, which is best if it is not stuffy the lotus root.The directions of lotus root heads in different rows should be alternated to each other, and the lotus root heads of the side row should be toward the field center.

Young Redswamp Crayfish Stocking

Stocking time

When most plants show leaves out of the water, the young redswamp crayfishes with the body length of 3-4 cm are put into the field.

Stocking density

About 75 000 to 90 000 young redswamp crayfishes per hectare are put into the field.

Stocking method

The young crayfishes should be put into the shallow water region with abundant aquatic plants to let them dive into the water by themselves. Or another way is to put the young crayfishes into the field water to immerse for 1 min, and then pick up and place for 1-2 min, and then immerse for 1 min, followed with several repetitions,which can improve the stocking survival rate[3].

Management

Feeding management

Feed quality Feed should comply with the provisions of NY 5072-2002.

Feed varieties The mixed feeding stuff of animal feedstuff and vegetable feed is in the majority.Animal feedstuff includes snail clam meat, fish meal,bone meal, earthworms and others,and plant feed includes cakes,cereals,wheat bran, corn and the leftovers from the agricultural and sideline products processing plant. It can also be combined with compound feed,and the application of compound feeds should comply with the provisions ofNY 5072-2002.

Feeding method and feeding quantity The feeding method is conducted according to the “four fix principle”,namely,fixed time,fixed amount,fixed place and fixed quality. The feed should be cast at the regions near to the crayfish groove with shallow water level, and the optimal amount of feed is that can make the crayfish eat up in 2-3 h. In general, 30% of the daily feeding amount is put before sunrise,and 70%after sunset[4].

Water quality management

Water quality requirement The aquaculture water is comply with the provisions of NY 5361-2010.

Water quality control Generally,new water is added every half month,and in high temperature seasons, 2-3 times a weak. In addition, based on the water quality, calcined lime is sprayed on the water every 20 d with the amount of 225-300 kg per hectare,which can on the one hand improve water quality, and on the other hand can increase the content of calcium ions in the water to promote the molting and growth of redswamp crayfish.

Water level control The water level control during the integrated farming is in the rule of shallow-deep-shallow.From the period of lotus root planting to leaf floating, the water depth in the field should be kept at 10-15 cm, and gradually increase to over 20 cm afterwards. In summer high temperature season, the water level should be maintained at 40-50 cm. And during the harvest time, the water level should reduce to about 30 cm.

Usage of oxygenation pump During the breeding process of redswamp crayfish, the dissolved oxygen in the pond water should be maintained at over 5 mg/L.When there is not enough oxygen in the water, oxygenation pump can be used at the noon of sunny days, and midnight of rainy days. If there appears a large amount of redswamp crayfish climbing to the aquatic plants,it should add oxygen as soon as possible.

Disease control and prevention

Disease control and prevention follows NY 5071-2002.

Topdressing

The compost organic manure or biogas slurry fertilizer should be applied to the field according to the water color of the pond and the growth of lotus plants. The application amount of organic manure is about 7 500 kg/hm2per time, which should be applied in the holes at 10-15 cm to the lotus root,and at different places for different application. The march Organic manure or biogas slurry fertilizer use finished timely according to the Ikeda color and lotus root growth. Organic fertilizer per usage at about 7 500 kg/hm2, the use should be from the lotus root 10-15 cm, grilled fertilizing into mud, each fertilizer transform position. The application amount of biogas slurry is about 15 000 kg/hm2for each time. And during the integrated farming period, 2-3 times of topdressing are applied.

Daily management

Production record The whole process of lotus root-redswamp crayfish integrated farming should be recorded,including lotus roots, source of young redswamp crayfish, source and application of input, the process of lotus root-redswamp crayfish integrated farming, the sales of lotus root and commercial redswamp crayfish.

Pond inspection The pond should be inspected every morning and evening, and if any abnormal found, corresponding control and prevention measures should be taken immediately.

Lotus Roots Harvest and Commercial Redswamp Crayfish Fishing

Lotus root harvest

The harvest time of lotus roots is relative long. Generally, if there are leaves turning yellow and many spade leaves appearing, it indicates that new lotus roots have grown up, and it is time to harvest the fresh lotus roots.Lotus roots are usually picked and put into market in mid July.

Commercial redswamp crayfish fishing

Redswamp crayfishes are usually fished in mid to late July. The fishing method is as follows: bamboo cages and crayfish pots are fixed at the crayfish grooves in the field in the evening and collected in the morning.The fishing could last till late September until all crayfishes have been caught.

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