The black soil region in northeastern China is a rain-fed agricultural area. Water is one of the key factors in determining crop yields. Changes in farmland soil moisture are affected by many factors, such as rainfall, solar radiation, wind speed, cultivated crops, soil texture, and organic matter content. In addition, cultivation practices also have an important impact on the changes in soil moisture. Electric Sightseeing Vehicle,Electric Tricycles With Roof,Concise Compact Electric Tricycle,Tourist And Tourist Trams FengXian Enland International Trading Co.,LTD , https://www.enlandvehicle.com
Increasing soil water storage capacity and reducing soil evaporation is one of the important tasks for farmland water management. For a long time, people have used and tried a variety of methods, such as mulching and straw mulching, the application of polymer water absorbent and water permeable film, the adoption of conservation tillage such as rotary tillage (less tillage) and no-tillage, and different ridge-direction planting methods. Attempts to establish a combination of agricultural, forestry, and grass ecosystems, and increase crop residue in the soil. Qin Ling et al. pointed out that increasing the use of peat in sandy soil can significantly improve the water retention capacity of the soil. For example, when the peat volume content is 15%, the field water holding capacity and saturated moisture content are 60.16% and 42.43% higher than that of pure sand, respectively. Wang Huixiao et al. pointed out that coverage is an effective measure to reduce soil evaporation, and stubble is a special cover farming measure and is the product of machine harvesting wheat. In 1994, the evaporation in the summer corn field under stubble and control conditions was measured at the Rucheng Station. The inhibitory effect of wheat aphid on soil evaporation in maize field continued until maturity. The average inhibition rate was 34.7% in the whole growth period.
However, there is no systematic report on the relationship between soil fertilization and soil moisture, water retention and evaporation. Through long-term location experiments and indoor simulation experiments, the effects of different fertilization measures on moisture content and water-holding and water-holding properties of farmland black soil were revealed, which can provide reference for farmland soil water management.
1 Background data of field trials Field trials were conducted at the Helen Agricultural Ecology Experimental Station of the Chinese Academy of Sciences for a period of 3 years. The test is part of a long-term water-fertilizer-coupled long-term positioning experiment with 4 fertilization treatments under natural precipitation conditions:
F1-no fertilizer, F2-medium quantifier, F3-high quantifier, F4-high quantifier and organic fertilizer. The cultivated crop was soybean in 2003 and maize in 2004 and 2005. F1, F2, F3 and F4 deal with the specific fertilization amount in 2003 (kg/hm2) N: 0, 13.5, 30.0 and 30.0; P(P2O5): 0, 34.5, 45.0 and 45.0; organic fertilizer 15 000.
The specific fertilization amount (kg/hm2) for the four treatments in 2004 and 2005 was N: 0, 96.0, 150.0, and 150.0; P: 0, 34.5, 75.0, and 75.0; and organic fertilizer 30,000. In addition to the above field tests, the indoor evaporation test was conducted using the soil in the above-mentioned test area. The test soil is typical black soil in China, and the organic carbon (mg/kg) is F1-24.4, F2-29.8, F3-26.6, F4-32.1. The rainfall in the experimental area from 2003 to 2005 is shown in Figure 1. 
Figure 1 Monthly mean precipitation from 2003 to 2005 2 Materials and methods The field test section was based on a neutron soil moisture meter in four different fertility treatment areas set up under natural rainfall conditions, using the CNC503B quad intelligent model. The sub-moisture meter continuously measured the soil moisture from 10cm to 210cm in four fertility management modes during the three-year period from 2003 to 2005. It began on April 5th and ended on October 5th. The depths monitored are 10cm, 20cm, 30cm, 40cm, 50 cm, 70 cm, 90 cm, 110 cm, 130 cm, 150 cm, 170 cm, 190 cm and 210 cm. Waterproof material is used between the residential area and the residential area, and the concrete pool is poured with reinforced concrete.
According to the samples taken from the above plots, evaporation tests were conducted under the temperature and humidity control conditions in the laboratory. The test adopted a split zone design with temperature as the main zone, humidity and soil species as subzones, and 3 replicates. The temperature treatment was 5°C, 10°C and 20°C, and the humidity treatment was 45%-55%, 65%-75% and 85%-95% of the maximum water holding capacity in the field.
The container used for the test was a 350 ml storage bottle. According to the bulk density and soil water content, the corresponding quality soil was weighed and compacted to 300 ml. Prior to placing the soil in the bottle, the amount of water that should be added is calculated based on the upper limit of the target soil moisture, and the moisture is uniformly mixed with the soil in a plastic bag. Twelve bottles treated with the same temperature were repeated as one time.
The 10°C treatment was performed in an artificial climate chamber; the 20e treatment was performed at a room temperature close to this temperature; the 5e treatment was performed in a cold storage, and both day and night were controlled at the same temperature. Evaporation was measured once every 4 days and then replenished to the upper limit of the target value. The soil is treated in the dark for 40 days. A total of 10 evaporations were measured.
The monthly wind speed data and monthly rainfall data were measured by the M520 Meteorological Automatic System. The average wind speed was every two minutes. Organic carbon was measured using an elemental analyzer. The cultivated crops are corn and soybeans. The yields of grain and straw (kg/hm2) treated with F1, F2, F3 and F4 were: 5056 and 2985, 7171 and 2149, 7050 and 2856, and 8356 and 5210 (The production trend in 2004 and 2005 was generally similar to that in 2003. In 2005, F2's straw production was higher than F3).
Field trials are considered as two-factor randomized trials, which are regarded as repeated during the interannual period. The laboratory culture part was statistically analyzed according to the crack zone design, and statistical analysis was performed using SAS software.
3 Results and analysis 3.1 Effect of different fertilization measures on total water content in soil profile From April to October in the growth period, the total average water content of 10 cm to 90 cm and 10 cm to 210 cm soil layers was calculated at each level for 3 years. It is: F1>F2>F3>F4 (see Table 1). In the range of 10cm to 210cm, the difference of soil moisture content between non-fertilizer, medium-quantity fertilizer, and high-quantity fertilizer was not significant, and the difference between high-quantity fertilizer and organic fertilizer reached a significant level of 5%. In the range of 0cm~90cm, where the crop has a large impact, there is no significant difference in soil moisture content between non-fertilizer and medium-quantity fertilizer, and there is no significant difference between high-quantity fertilizer and high-quantity fertilizer and organic fertilizer, but no fertilizer and medium amount. The difference between chemical fertilizers and high-quantity fertilizers and high-quantity fertilizers plus organic fertilizers was significant, reaching a level of 1%. The results showed that the treatment of fertilization, especially high-quantity fertilizer and high-quantity fertilizer plus organic fertilizer, significantly affected the soil water content, especially in the range of 10cm to 90cm where the crop had a large impact. 
Table 1 Total Mean of Soil Moisture Levels 3.2 Effect of Different Fertilization Measures on Soil Moisture Content at Different Levels From the average number of growing stages, there is a 5% level of water content in all treatments within 10cm to 70cm. Significant difference between the levels within the range of 70cm to 210cm was not significant (data not available).
It can be seen from Figure 2 that the effect of the fertilization measures starts at about 10cm and ends at about 70cm. Within this level, the water content of the quantified fertilizer and non-fertilizer in Shizhong was higher, and the difference between the two was not significant; the water content of high-quantity fertilizer and high-quantity fertilizer plus organic fertilizer was low, and the difference between the two was low. Not obvious. The reason for this difference is that the application of high-quantity fertilizers and high-quantity fertilizers plus organic fertilizers resulted in more vigorous crop growth, higher biomass production, and thus more water consumption. In the range of 70cm to 90cm soil layer, the water content has changed. After the depth exceeds 90cm, the application of high-quantity fertilizer treatment water content exceeds the other three treatments, with a clear increase trend, and the application of high-quantity fertilizer and organic fertilizer treatment However, there is no obvious change, showing that the application of chemical fertilizers has a significant water retention effect, while the application of organic fertilizers increases the loose air permeability of the soil, thus increasing evaporation. The impact of crop water consumption on groundwater was as deep as 250 cm, with no effect at 270 cm (data not provided). The two treatments with more fertilization are larger than those with no treatment and less fertilization. 
Fig. 2 Average moisture content of soil profile from 2003 to 2005 3.3 Seasonal variation of effect of different fertilization measures on soil moisture content at different levels In April, crops had less influence on soil moisture content. In this period, the water content of F3 and F4 was lower in the range of 10cm to 90cm, and the depth was over 90cm. F3 was significantly higher than other treatments. This period was mainly influenced by the moisture status of the previous year (Figure 3-a).
After entering the month of May, the gap between F1 and F2 and F3 and F4 has a tendency to shrink with the beginning of crop root activity. In June, this trend has further narrowed (Figure 3-b). After entering the rainy season in July and August, the difference between F1 and F2 and F3 and F4 has further increased (Figure 3-c) until the end of the trial in October. In the depth range of more than 90cm, the gap between F3 and other treatments began to shrink from June and began to shrink significantly in August until the end of the trial in October. According to the analysis of limited data, this gap is gradually widening in the winter and reaches a greater value in April and May. 
Figure 3 The average soil moisture content plus organic fertilizer treatment, in the early growth period, that is, without crop growth, its water content is also very low, there are two reasons, one is the application of organic fertilizer treatment, One year consumes more water; the other is the residue of straw, etc., in the organic fertilizer, which loosens the soil and leads to a decrease in water retention. In July, the rainfall reached its peak, but the soil moisture reached its trough (Figure 4). The direct cause of this trough is the water consumption of the crop. At 10cm, the change of each treatment did not show regularity until the middle of July; from the depth of 20cm, the treatment showed a significant difference, especially from June to September; when the depth was 50cm, the treatment The gap has shrunk, but there is still a clear pattern that changes with the season; at 130cm, the trough in July is still visible until 170cm; at 190cm, no sign of seasonal change has been observed (Figure 5). 
Fig. 4 Average water content at each level in the depth from 10cm to 210cm from 2003 to 2005 
Fig. 5 Seasonal variation of soil water content at different levels 3.4 Analysis of different fertilizer application and soil moisture retention Fig. 2 and Fig. 3 show that the treatment of high-quantity fertilizer was applied. At the same time as high yield, the bottom layer below 70 cm was preserved. Moisture content, and the application of the same high-quantity fertilizer with organic fertilizer treatment, the deep water content is not a single application of high-quantitative fertilizer high, which is related to the organic fertilizer increased soil evaporation, with the role of drainage.
3.5 Evaporation Analysis 3.5.1 The characteristics of soil evaporation in different fertilization practices. Statistical analysis of laboratory tests showed that there was a significant difference between the net evaporation per 4 days in 20cm soil and the quantification in the application (Table 2). Although the difference between the two treatments is not significant, it can be assumed that there is a large amount of evaporation in the non-fertilized soil and a decrease in the amount of soil evaporation applied to the chemical fertilizer. In addition, the application of chemical fertilizers and the application of organic fertilizers at the same time have a certain amount of air permeability, which increases the evaporation amount to some extent. 
Table 2 Average evaporation of different treatment 4d 3.5.2 Interaction of temperature and humidity on evaporation. Under the condition of suitable water content (75%), the non-fertilizer treatment evaporation is higher than other fertilization treatments. At 5°C and 20°C, the non-fertilizer treatment evaporation was higher than the application of high-quantity fertilizer plus organic fertilizer, and the difference was 5% significant.
Under the condition of higher temperature (20°C) and more humid (95%), the evaporation of the application of high-quantity fertilizer plus organic fertilizer was significantly higher than that of other treatments, indicating that application of organic fertilizer can not only improve soil water retention performance, but also The function of platoons.
At 10°C and relatively arid conditions, the application of high-quantity fertilizers has a large evaporation. It can be seen that when a large amount of chemical fertilizer is used alone, water loss is more likely to occur under relatively low temperature and relatively dry conditions.
3.5.3 Effect of Temperature on Soil Evaporation of Each Treatment. There are significant differences in the evaporation conditions under different temperature conditions, ie there is a significant difference of 5% between the treatment at 20°C and the treatment at 5°C and 10°C.
There was no significant difference between the 5°C and 10°C treatments.
3.5.4 Effect of Soil Moisture on Soil Evaporation of Various Treatments.
The overall trend of the difference in evaporation between different humidity treatments is that the evaporation decreases with increasing moisture content, but does not reach a significant level. Under the relative high temperature conditions of 10°C~20°C, the evaporation conditions of non-fertilizer application, high-quantity fertilizer application, and high-quantity fertilizer plus organic fertilizer treatment varied significantly with humidity. The non-fertilizer application and the application of chemical fertilizer treatment decreased evaporation with the increase of soil water content. Treatments with organic fertilizers have increased evaporation in the presence of high water content.
4 Conclusions The long-term application of fertilizers compared with the non-fertilizer treatment, the soil moisture content has undergone a significant change. Different performance in different growth stages. Fertilizer treatment, especially the application of high-quantity fertilizers and high-quantity fertilizers plus organic fertilizers, has a significant impact on the soil moisture changes due to strong crop growth, and the main impact area is 10cm to 90cm soil layers.
By analyzing the total average water content in the growth period, it is pointed out that there is a significant difference of 5% in the water content between all levels within the range of 10cm to 70cm. The water content in the application of quantified fertilizer and non-fertilizer was relatively high. There was no significant difference between the two. The water content of high-quantity fertilizer and high-quantity fertilizer plus organic fertilizer was relatively low. There was no significant difference between the two. After a depth of more than 90 cm, the application of high-quantity fertilizers exceeds the other three treatments, and the application of a relatively high amount of fertilizer has a significant water retention effect. The application of organic fertilizers increases the loose air permeability of the soil and thus increases evaporation. The impact of crop water consumption on groundwater was as deep as 250 cm, and no effect was seen at 270 cm.
The two treatments with more fertilization are larger than those with no treatment and less fertilization.
In April, the water situation was mainly affected by the previous year.
With the beginning of crop root activity in May, the difference between F1 and F2 and F3 and F4 has a tendency to shrink; after entering the rainy season in July and August, due to the difference in crop water consumption between F1 and F2 and F3 and F4 The difference was further increased until the end of the experiment in October, although the rainfall reached its peak, but the soil moisture content has reached its trough (Figure 4, Figure 5). In the depth of more than 90cm, the water content advantage of F3 and other treatments began to shrink from June, and began to shrink significantly in August until the end of the test. At 10cm, the change of each treatment did not show regularity until the middle of July; from the depth of 20cm, the treatment showed a significant difference, especially from June to September; when the depth was 50cm, the treatment The gap is narrowing, but the pattern of seasonal changes is still visible until 170 cm. Starting from 190cm, no signs of seasonal change have been seen.
The treatment of high-quantity fertilizers was applied, and at the same time as high-yield, the water content of the soil below 70 cm was preserved, and the treatment with the same high-quantity fertilizer and organic fertilizer was applied, and the deep water content was not as high as high-quantity fertilizer. This is related to organic fertilizers that increase soil evaporation and have a drainage function.
Surface soil evaporation tests in the laboratory showed that application of chemical fertilizers reduced evaporation of soil moisture and improved water retention.
Applying chemical fertilizers while applying organic fertilizers improves the permeability of the soil. The application of organic fertilizer treatment has the following characteristics: In the case of high water content, there is the role of drainage; in the case of moderate water content, the evaporation is the smallest, there is the role of water retention.
In the case of non-fertilizer treatment, the maximum evaporation occurs under suitable conditions of moisture and drought. In the case of large soil moisture content, the evaporation is slow, and relatively does not have the effect of water retention and drainage.