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Nanjing Institute of Industry Technology, Nanjing 210023, China

Abstract　Shallow planting of the rice seedlings is an important factor for getting high yield as it can increase the effective tillers on the low-node of the stem. The 2ZB-79 shallow rice seedling transplanter combined the advantages of shallow planting of the seedling-casting rice transplanter and orderly planting of the traditional rice transplanter. The principle of this kind of machine is firstly to cut the standardization nursery rice seedlings with rug soil into many small pieces, and then to plant the small pieces composed of pot soil and some seedlings on it to the field surface in order, only shallowly planted on the very top part of paddy soil. Not only it can keep the performance of planting shallowly and orderly, but also simplify many mechanisms for transition, separation, and plantation of rice seedlings. It is a new type of rice seedling transplanter called laying-type up to now to get higher efficiency when working and higher yield for rice production. This paper will introduce its developing results and analyze the comparative experiments.

Key words　Agricultural machinery, Rice mechanization, Transplanter, Experiment

1　Introduction

Shallow planting is a new type of planting technology extended in the early 1990s in China, and it can increase the low-node effective tiller of rice to get higher yield. Thus, casting seedling technology represented by seedling-casting transplanter developed rapidly. The seedlings are cast disorderly in the field, making the shallow and orderly planting become impossible. Most agriculturists considered that orderly transplanting is good for ventilating and transmitting light and could take full advantage of group cultivation. The machine technique could be improved then to wide row spacing with narrow hole spacing which possesses many more advantages than the square cultivating or disorderly planting. Square planting results easily in radiant individuals, with big leaf angle, weak leaves, strong competition, shade in the low layers, low group quality in later period, poor ventilation and light condition,small green area, little accumulation of dry matters and serious infestation of insects. Casting seedlings is disorderly, causing the poor ventilation and light condition in growth period so that the growth in later period will be influenced badly and making the harvest become more difficult.

2　Main technical characteristics and parameters

The whole mechanism of seedling managing machine is included by working and transitive parts. The former is made up of base powered by paddy solo-wheel, frame of engine, walking wheel, steer wheel, frame of tow, and so on, all of which are applied commonly in China at present. The latter consists of gimbals, assembly to move box, feeding box, seedling float and planting wheel. The main parameters of them are shown in Table 1.

This machine is characterized by many creative features. (i) The core planting wheel adopted integral three-row seedling hands which can take seedlings three times, instead of using traditional planting mechanism (single or double seedling hands) which can only get seedlings one or two times in one cycle, this can increase efficiency and reduce the vibration greatly. (ii) The exchangeable type of machine is researched to adapt different row spacing, so that the user can get 238 mm or 300 mm row spacing through disassembling and assembling to meet the different agronomic standard in different regions of China. (iii) The device to reduce the side accumulation of soil is developed. (iv) The whole ring belt to transmit seedlings is designed to improve the consistence of transmitting seedlings. (v) The adjustable equipment of transmitting seedlings longitudinally is produced to widen the application scope.

3　Working principle of the rice seedling arranging machine

The working principle of the rice seedling-arranging machine is showing in Fig.1. When the 2ZB-79 shallow rice transplanter works, the rice seedling claw distributing and taking seedlings is driven into the seedling gate by the distributive wheel and the track of the claw is controlled by the cam track. At the moment when the seedling claw goes out the seedling gate with seedlings, the crank wheels run away the cam track simultaneously. Then the spring resets and bumps onto the stop block. This accelerates seedling claw to rotate certain angle to the limited position. It the same time when the seedling claw is rotating, distributing seedling plate speeds up to push rice seedlings. This makes seedlings get off the seedling claw and stay on the earth. Then, the procedure is completed. Seedlings get off the seedling claw at certain speed with a series of synthetic effects such as acceleration, push, cast and so on. Thus, seedlings not only can be planted in paddy soil but also be able to stand on soil surface better. The largest difference of the mechanism between transplanting rice seedling machine and the 2ZB-79 shallow rice transplanter is that the seedling claw (detaching pin) must be in soil during transplanting rice seedlings while it needn’t be in soil when arranging seedlings. Then the advantage of seedlings laying machine is that it can not only increase rice yield by shallow planting but also reduce the machinery friction caused by entering soil and simplify its structure.

Table 1　Main parameters of 2ZB-79 shallow rice transplanter

4　Experiment of the 2ZB-79 shallow rice transplanter

It takes six years to make productive replicate to test the performance of the laying machine on single crop of rice, first crop of double rice of crop rotation, second crop of double rice of crop rotation in 10 regions of Jiangsu Province, Zhejiang Province,etc. The performance of the machine is listed in Table 2. The comparison of growth and output is listed in Table 3 through Table 5.

Note: 1. cam track, 2. crank, 3. row of seedling claw, 4. distributing seedling axle, 5. stop block, 6. reset spring, 7. seedling releaser, 8. seedling claw, 9. seedling gate, 10. feeding box.

Fig.1Structureofdistributingseedlingdevice

4.1Performanceofthe2ZB-79shallowricetransplanterAny performance of the 2ZB-79 shallow rice transplanter meets the needs of local agronomy. There is little increase in yield using seedlings laying machine than using transplanting seedling machine or planting manually. The reason of high yield lies in advantages of more effective low-node tilling, faster tiller rate and more ears, etc, after rooting of seedling in field. The contrast test between planting manually, transplanting rice seedlings using machine, casting seedlings using machine and laying seedling indicates that the average rice yield of using seedlings laying machine is 5.35%, 6.14%, and 0.27% higher than using manual transplant, rice transplanter and cast seedling machine respectively.

4.2AnalysesofperformanceThe rate of damaged seedlings is very low, with the minimum rate of 0.12%, which would contribute to the growth of seedlings in late period. The rate of leaving out seedlings is also low, with the minimum rate of 1% and average rate of 2.89%. The 2ZB-79 shallow rice transplanter runs evenly and steadily, its maximum evenness degree is 98.1%, and average relative evenness degree is as high as 106.4%. The 2ZB-79 shallow rice transplanter has higher efficiency. Its average productivity of pure working hour is 0.34 ha/h, while the productivity of the rice transplanter for the 2ZT-78 is 0.2 ha/h. The row spacing is constant and coefficient of variation is less than 5%.

Table 2　Test results of the 2ZB-79 shallow rice transplanter

RegionLujia village,Fuyang, ZhejiangYuexi, Suzhou,JiangsuJingdu, Yangzhou,JiangsuYellow SeaFarm, JiangsuDamaged seedlings rate before transplanting ∥% 0000Soil compaction ∥cm10.88.3/12.2Performance qualityAverage amount of seedlings ∥ plant5.756.243.74.6Average depth of arranging ∥mm4.50.920.460.3Actual arranging holes ∥104/ha42.10826.01334.0534.44Rate of leave out arranging ∥%31.084.74.8Rate of falling seedlings ∥%41.63.92.6Rate of damaged seedlings ∥% 0.120.163.22.1Qualified range of evenness degree ∥ hole3-93-92-72-7Qualified rate of evenness degree ∥%84.33848890Relative evenness degree∥%104112103.5106Coefficient of variation of row spacing ∥%<5<53.24.69Productivity during pure work hour ∥ha/h0.320.330.390.45

Table 3　Grain structure of ear and yield for different planting patterns of single crop rice

Table 4　Yield of first crop of double rice of crop rotation with different planting patterns in Yuexi

Table 5　Yield of single crop of rice with different transplanting patterns in Yuexi

5　Conclusions

(i) The 2ZB-79 shallow rice transplanter is a new type of high efficient planting machine with the development of rice light planting technology. The technique of the 2ZB-79 shallow rice transplanter, integrating the production advantages of shallow and orderly planting, realized significant yield increase.

(ii) The 2ZB-79 shallow rice transplanter is a type of cheap machine. As a consequence of planting the seedling into the soil, the rice seedlings transplanting machine has a complicated mechanism with more malfunctions, more wearing parts and high cost. On the contrary, because of planting seedlings shallowly in soil, not entering soil of separating mechanism and simple mechanism, the cost of the 2ZB-79 shallow rice transplanter is low, with less damaging part easily and low using cost. According to current trial-manufacturing cost, the cost of the 2ZB-79 shallow rice transplanter is about 10% lower than that of the rice seedling-transplanting sample machine.

(iii) The 2ZB-79 shallow rice transplanter has high productivity and has wide application prospect. It has great realistic significance for improving rural economy and reducing the labor intensity. It provides a new type of rice light transplanting machine for the rice planting mechanization in China.