Haixin WANG, Jingbo YAN, Huixin WANG, Feng SHI
Liaoning Sandy Lands Improvement and Use Research Institute, Fuxin 123000, China
Liaoxi (western regions of Liao River)and Liaobei(northern regions of Liao River)are situated in the south, north and northwest of Horqin Sandy Land, bordering Jilin and Inner Mongolia, shaping a narrow belt with distances from east to west at 360 km and from south to north at 100 km,and an area of 1.986 million hm2[1].It has a continental monsoon climate,characterized by more gales,few precipitation and heavy evaporation. The soils are dominated by sandy soils and sandy loam soils, suitable for maize,peanuts or coarse cereals.Because of excessive cultivation, grazing and reclamation, desertification lands total 1.138 7 hm2, taking up to 7.7% of provincial lands,of which the desertification area from farmlands reaches 28 hm2,accounting for 6.7%of the provincial level[1]. It is notable that desertification of farmlands is a result of multiple factors, and inappropriate cultivation should be the dominant one[2-4].Recently,the area of peanut in Liaoning Province has exceeded 350 000 hm2,becoming the 3rdlargest crop after maize and rice. Nevertheless, after harvest, surface soils undertake considerable wind erosion without crop residues on lands, deteriorated by inappropriate cultivation, resulting in serious water and nutrient losses, and low yield[5-6]. Therefore, the research explored anti-wind erosion effect of peanut stubble and the effects on peanut growth in fallow period.
The test region was Zhanggutai experiment station of Liaoning Sandy Lands Improvement and Use Research Institute, in the southeast of Horqin Sandy Land. It has a continental monsoon climate. Specifically,annual average wind speed is 3.33 m/s, sandstorms occur 240 times at 5 m/s, and gale day with grade over 6 reaches 46 d. What’s more, annual precipitation tends to be volatile in the range of 300-500 mm, and uneven spatial and temporal distribution, and the evaporation amount of soils proves 4 times as high as precipitation[6]. The soils are wind-blown soils and diameter of 90% soil granule keeps in 0.005-0.5 mm,with loose structure.In addition, soil contains few nutrientsand organic matter is below 1%. The frost-free period lasts about 150 d.
During fallow period, 4 cultivation treatments were designed in the test.Specifically, on October 20, treatment①referred to that the farmlands were plowed with depth of 25-28 cm, and pressed when surface soils thaw of the following year;treatment ②referred to that the farmlands were under rotary cultivation in autumn with depth of 12-15 cm, without pressing; treatment ③referred to that soils were ridged in autumn with height of 10-12 cm and pressed when surface soils thaw of the following year;treatment ④referred to that farmlands were under rotatorcultivation with depth of 12-15 cm,1-2 d before sowing in spring. It is notable that every treatment area totals 667 m2,and the sample area at 30 m2,with three repetitions. The control group was the treatment where soils were plowed as per traditional method with depth of 25-28 cm.Peanuts were then continued sown of thefollowing year and the management was the same as local method.
Physical and chemical properties were measured of the 4 treatments.Specifically, the degree of wind erosion on surface soils was measured as per benchmarks-plugging method, soil moisture was as per dryingmethod;total N was as per kjeldah method;total P as per acid soluble-Mo-Sb colorimetry;hydrolyzable nitrogen was as per kjeldahl method for nitrogen determination; soil bulk density and total porosity as per cutting-ring method.Furthermore, peanut growth and pod yield were measured accordingly of thefollowing year.
Wind erosion degree of surface soils as per different methods were measured from March to May of spring of the following year. As shown in Table 1, it was observed that the degree of wind erosion by plowing in autumn was 0.6 cm below compared with rotary tillage in autumn, 0.2 cm fewer than that of autumn rotary tillage, and 0.1 cm fewer than rotary tillage before spring sowing, which suggested that soil wind erosion degree was the lightest. On May 3, it was observed thatthedegree of wind erosion by autumn plowing was 0.2 cm more than that by autumn rotary, 0.9 cm more than that of autumn cultivation and 1.1 cm more than rotary cultivation before spring sowing, incorporating serious wind erosion.
Based on the degree of soil wind erosion, it can be concluded that surface soils were dominated by unevensized and rugged granules on March 3 by plowing in autumn, which reduces ground wind speed and wind erosion[7-9]. On May 3, because soil thawed after pressed when surface soils thawed, wind erosion became much dramatic. By rotary cultivation in autumn, it was observed twice that wind erosion was much strong, for the soils under rotary cultivation deteriorated wind erosion of soils. What’s more,the soils under ridging in autumn became more rugged, strengthening wind-resistance, weakening ground wind speed and reducing wind erosion on ground soils.In addition,rotary cultivation before spring sowing, soils tightened during fallow period, improving resistance capacity against wind and reducing wind erosion on ground soils.
Table 1 The degree of wind erosion on soils as per different cultivation methods
Table 2 Moisture content of soils by different cultivation methods
Table 3 Nutrient contents of soils by differentcultivation methods
Before spring sowing of the following year, moisture contents of soil layers of 0-30 cm were measured. As shown in Table 2, moisture content by plowing in autumn was 6.1% lower compared with rotary cultivation with depth of 0-10 cm, 1.51% lower compared with rotary cultivation with depth of 10-20 cm, and 20.7% lower compared with rotary cultivation with depth of 20-30 cm.Compared with ridging in autumn with depth of 0-10 cm, moisture content by autumn plowing was13.8% lower, 21.9% lower compared with ridging with depth of 10-20 cm,26.4% lower compared with riding in autumn with depth of 20-30 cm. Additionally, moisture content by plowing in autumn was 32.3%lower compared with rotary cultivation in spring with depth of 0-10 cm, 37.7% lower compared with rotary cultivation in spring with depth of 10-20 cm and 38.3%lower compared with rotary cultivation in spring with depth of 20-30 cm.
According to measurements of the four cultivation methods, from plowing in autumn to the date of surface soils thawing of thefollowing year, soil porosity was large, and water evaporation proved significant,leading to low moisture content of soils[10-11]. Of autumn rotary and autumn ridging, the latter performed better in water maintenance. Before sowing in spring, because of fallowing period, surface soils tightened and grew coarser, reducing water evaporation,and improving water maintenance.
Before sowing in spring, soil samples were collected from soil depths of 0-20 cm as per four cultivation methods andnutrient contents were measured after naturally drying.As shown in Table 3, by autumn plowing,total N reduced by 0.079%,total P decreased by 0.006 9%, hydrolyzable nitrogen decreased by 1.01 mg/100 g soils, and organic matter reduced by 0.621%,compared with autumn rotary cultivation. By autumn plowing, total N reduced by 0.023 3% compared with autumn ridging, total P reduced by 0.015 4%, hydrolyzable nitrogen decreased by 3.71 mg/100 g soils, and organic matter decreased by 0.715 5%,compared with autumn ridging.By autumn plowing, total N reduced by 0.030 5%,total P reduced by 0.017%,hydrolyzable nitrogenreduced by 3.77 mg/100 g soils,and organic matter reduced by 0.728 8%compared with rotary cultivation before spring sowing.It can be concluded that nutrient contents by rotary cultivation before spring sowing maintained higher compared with rest cultivation methods.
According to measurements of soil nutrients by the 4 cultivation methods, by autumn plowing, total N, total P, hydrolyzable nitrogen and organic matter contents all kept lower, because of soil turnover and serious wind erosion after pressing; by rotary cultivation in autumn, total N, total P, hydrolyzable nitrogen and organic matter contents were all lower, resulting from loose surface soils and serious wind erosion; by ridging in autumn, soil nutrients lost less due to slight wind erosion;rotary cultivation before sowing in spring,surface soils were least eroded and the least nutrients lost.These indicated that nutrient loss in soils is of direct relationship with wind erosion.
As shown in Table 3, soil bulk density by plowing in autumn reduced by 0.14 g/cm2, and total porosity increased by 2.2%compared with rotary cultivation in autumn. By plowing in autumn,soil bulk density decreased by 0.15 g/cm3and total porosity improved by 5.6%,compared with ridging in autumn; soil bulk density decreased by 0.16 g/cm3and total porosity increased by 9.8% compared with rotary cultivation in spring.
As shown in Table 4,soil structure was improved, soil bulk density declined, and total porosity improved by plowing in autumn; soil bulk density declined, total porosity increased and soil structure performed poorer by rotary cultivation in autumn compared with plowing in autumn; by ridging in autumn, surface soils were loose, and the deep soils tightened, and the soil structure was poorer compared with plowing in autumn. During fallow period, soil bulk density was high and total porosity was lower with peanut stubbles on fields. What’s more,soil physic-chemical characters were improved.
Table 4 Soil layer structure by different cultivation methods
Table 5 Effects of different cultivation methods on ecological characters and yields
As shown in Table 5, peanut was shorter by plowing or rotary cultivation in autumn, and grew health by ridging in autumn or before sowing in spring.Furthermore, the number of peanut was one fewer by plowing in autumn compared with rotary cultivation in autumn, and two fewer compared withridging in autumn or before spring sowing. Peanut weight was 0.6 g lighter by plowing in autumn compared with rotary cultivation in autumn, 0.8 g lighter compared with ridging in autumn, and 0.9 g lighter compared with ridging before spring sowing. In terms of hundred-fruit weight, it was 0.2 g lighter by plowing in autumn compared with rotary cultivation in autumn, 0.3 g lighter compared with ridging in autumn, and 0.8 g lighter compared with rotary cultivation in spring.As for hundred-pod weight, by plowing in autumn, it was 0.3 g lighter compared with rotary in autumn, 0.8 g lighter compared with ridging in autumn, and 0.8 g lighter compared with rotary cultivation in spring. For yield of peanuts,the yield reduced by 2.6% by rotary cultivation compared with plowing in autumn, increased by 2.5% by ridging in autumn, and increased by 5.3%compared with rotary cultivation in spring. These indicated that the yield of peanut proved the best by rotary before spring sowing.
The measurements of peanut growth and yield demonstrated that the differences of yield by autumn plowing with the rest were mainly caused by soil turnover, deteriorated by surface soil erosion.By autumn rotary cultivation, soils would undergo serious wind erosion, and water and nutrients would be lost, resulting in lower yield. By autumn ridging, less water and fewer nutrients would lose,and yield would increase.By rotary cultivation in spring, because of soil reclamation 2 d before sowing, the loss of water or nutrients proved small,so that seedlings grew fully and strong,flowers were much more, and fruits grew more and full.
The research indicated that rotary cultivation before spring sowing proved more significant in anti-wind erosion during fallow period with peanut stubbles on field, followed by autumn ridging, plowing, and rotary cultivation in autumn. Hence, it is effective for improving anti-wind erosion by no-tillage during fallow period and land reclamation before sowing in semi-dry areas.
The field with peanut stubbles performs good anti-erosion effects,supplemented by rotary cultivation before sowing during fallow period. In order to create better soil environment for peanut roots’growth,deeply plowing should be conducted every 2 -3 years to prevent soil erosion and improve soil structure, which not only maintains high and stable yield of peanut and soil sustainable use of lands.
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Agricultural Science & Technology2015年1期