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Soil Fertility and Fertilizers, 8th Edition
Appropriate fertilizer application is an important management practice to improve soil fertility and quality in the red soil regions of China.
Results showed that the soil pH was the lowest with an average of 5. Thus, these indicated that organic manure should be recommended to improve soil fertility in this region and K fertilizer should be simultaneously applied considering the soil K contents. Considering the long-term fertilizer efficiency, our results also suggest that annual straw returning application could improve soil fertility in this trial region.
This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. The authors declare that no additional external funding was received for this study.
The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing interests: The authors have declared that no competing interests exist. In these red soil regions, Rice Oryza sativa L. Paddy soil, formed under interchange between drying and wetting rice field conditions, is considered to be the most important soil resource for the food security of China . In recent years, due to the rapid population growth and a continuous decline in the amount of cultivated land area, the rate of fertilizer application keeps on rising in these regions in order to obtain high crop production in agriculture .
Nevertheless, instead of improving the soil structure and fertility, the long-term inappropriate fertilization has caused severe degradation of red soils, characterized by high acidity, low nutrients and a disturbed, unbalanced ecosystem . Recently, soil quality has gained attention as a result of environmental issues related to soil degradation and production sustainability under different farming systems .
It has been considered by previous researches that the concentrations of soil nutrients e. Soil pH affects the chemical reactions in soil . Soil organic components, such as soil organic carbon SOC or total N TN are the most critical indices of paddy soil fertility . Dynamics of SOC and TN storage in agricultural soils drives microbial activity and nutrient cycles, promotes soil physical properties and water retention capacity, and reduces erosion .
Moreover, it has been recognized that soil available nutrients including N, P and K , coming from mineralization and available components of fertilizer, can be directly absorbed by plants, contributing greatly to the soil fertility . With the development of agricultural production, fertilization has been widely used as a common management practice to maintain soil fertility and crop yields .
Long-term field experiments LTFEs using different agronomic management can provide direct observations of changes in soil quality and fertility and can be predictions of future soil productivity and soil environment interactions  , . Over past decades, a great number of long-term experiments were initiated to examine the effects of fertilization on soil fertility in the world  — . Some studies have documented that the use of fertilizers was necessary, and that continuous fertilizer application increased the concentrations of SOC, TN and other nutrients in plough layers compared with the initial value at the beginning of the experiment  — .
Manure amendments markedly increased the contents of SOC, TN, and other available nutrients, and reduced soil acidification  , .
However, other studies have shown that the continued use of fertilizers may result in the decline of soil quality and productivity  , . Long-term application of fertilizer was inadequate to maintain levels of nutrients, the SOC and TN significantly decreasing under the fertilizer treatment and the available N AN , available P AP and available K AK did not show clear changes with time or between treatments despite some variation  , .
Qianyanzhou experimental station, which was founded in by Chinese Academy of Sciences CAS , is noted for its studies on the integrated development and management of natural resources in red earth hilly regions.
These experiments have provided basic data for research into paddy soil. However, most of them dealt with different chemical fertilizer rates in long-term experiments but few studies focused on different types of fertilizers such as green manure and rice straw return affecting the soil fertility.
A thorough understanding of how these fertilizers and varying management practices affect the long-term soil fertility of conventional cropping systems is still lacking in Qianyanzhou region, one of the most important typical red earth hill regions in China. In this study, five fertilization treatments no fertilizer, rice straw return, chemical fertilizer, organic manure and green manure were applied.
Our objectives were to i assess the changes of soil fertility parameters in Qianyanzhou from to ii evaluate the effects of different fertilization treatments on soil fertility parameters, and iii put forward suggestions to improve soil fertility in agricultural regions of southern China. The average elevation is approximately m, and relative relief is 20—50 m. Qianyanzhou Experimental Station has a subtropical monsoon climate.
According to the statistics of the meteorological data, the mean annual temperature at this site is The annual precipitation and evaporation are Our experimental field is located in the flat floodplain where the soil-forming parent material consists of red sandstone and sandy conglomerate. Based on the investigation and analysis before our experiment, it can be concluded that paddy soil is the main soil type with bulk density of 1.
Soil samples for — were not analyzed dashed lines. A long-term fertilization experiment was conducted initially in under a double rice cropping system rice-rice-winter fallow which is one of the most common cropping systems in the region.
Summer rice was sown at the end of April and harvested in July. Winter rice was sown at the end of July and harvested in November. During the growing season, hand weeding was done to control weeds. All treatments were arranged in a randomized block design with three replications  ,  ,  , totalling 15 plots.
These fertilization systems were chosen based on several common fertilization experiences from local farmers. All pig manure used in our experiment came from a pig farm in Taihe County, where the composting-process was conducted at high temperatures and a good organic fertilizer was obtained after a few months of fermentation by sterilization, deodorization, and so on  , .
Soil samples in the 15 plots were collected annually during — at 7—10 days after the harvest of the late rice. To reflect the real effect of long-term fertilization on the soil fertility, the data in the first 5 years of this experiment were not obtained to analyze in our paper. In each plot, soils were sampled with an auger with 5 cm internal diameter in the plough layer 0—20 cm at five randomly selected locations and then mixed as one sample  ,  , .
All fresh soil samples were air-dried and sieved through a 2. Soil physical and chemical properties were measured using the methods described by Bao . AN was determined by using a micro-diffusion technique after alkaline hydrolysis. AP was determined by the Olsen method. Then the annual values under different treatments were used to investigate the dynamics of nutrient contents during the whole period.
All statistical analyses were performed using the SPSS software package version The average soil pH was shown in Fig. The soil pH was the lowest in CK with an average of 5.
In OM. During to , the soil pH in NPK treatment appeared relatively stable despite some slight drop with the time Fig. However, the values in other treatments showed a clear decline trend with time despite some variations. In the beginning years after fertilization, there was no evident difference in pH among all treatments, but eventually the soil pH in CK reduced dramatically and declined sharply from 5.
The SOC in different treatments had a similar trend over time Fig. From to , the SOC showed a clear increase with time due to fertilization, rising from initial 9.
Then SOC content dropped sharply but quickly reached at stable level. In the first few years, TN content tended to increase rapidly in the OM treatment from 1.
Thereafter, both of them declined and then maintained a certain level. In the last two years of the experiment period, all the five treatments displayed similar trends without a significant difference varying slightly between 8.
AN in the OM treatment obviously increased with time due to fertilization at the beginning, and then the value tended to rise with a slight fluctuation before remaining at the highest level in comparison to the other treatments. Specifically, the value rose sharply in the first few years of fertilization However, the significant changes of AK in other treatments with time were not observed, maintaining at a stable and low level.
Many experiments have been conducted on the relationship between fertilization and soil pH  , . Some studies demonstrated that the soil pH was decreased to a certain extent with different fertilizer treatments . In our study, the soil pH tended to drop in different treatments with time Fig. It has been reported that the application of alkaline fertilizer e. In addition, the application of organic manure could improve soil acidity by increasing the soil organic matter, promoting the soil maturation, improving the soil structure, and enhancing the soil base saturation percentage, which is in line with Zhang  and Li .
Moreover, studies showed that the soil pH in CK was lower than the initial value, which indicated that the acid deposition could have a great influence on the soil acidification in this trial region .
Since a too high or too low pH is harmful to the crop growth, it might be a practicable measure to establish the proper range of soil pH through fertilizer use. Soil organic matter is a key contributor to soil due to its capacity to affect plant growth indirectly and directly . As SOC and TN constitute heterogeneous mixtures of organic substances, they are widely used as the main parameters for evaluating soil fertility .
Meanwhile, human activities such as fertilizer practices and cropping systems play a key role in the regulation of C and N contents in agricultural soils . This may be because both the application of organic manure and chemical fertilizer can improve soil aggregation, soil water retention, and reduce bulk density of the soil in the plough layer, promoting crop growth and the return of more root residues to the soil . In farmland ecosystems, pig manure is easy to accumulate in soil and has lower ammonia losses than other fertilizers  , so the TN concentration was significantly increased by continual annual OM applications compared to the other treatments Fig.
It is known that fertilization is crucial for maintaining soil available nutrient levels, because fertilization ensures the largely constant presence of active microorganisms and the regular dynamic of biomass carbon . Our research also showed that soil available nutrient contents were significantly affected by different fertilization treatments. It has also been reported by Huang  that significant AN and AP increases were observed in the manure-applied treatments.
Unlike AN and AP, AK was the highest in NPK treatments in our results, followed by the OM treatments, demonstrating that the K supplement from chemical and manure fertilizers are important and this may be the most advantageous way to solve the problem in China, where K resources are quite limited.
Previous studies have shown that application of rice straw significantly increased available K while increasing organic matter contents  , . Previous study had described that the decomposition process of green manure as a fresh organic matter was very slow and complicated, affected by soil temperature, moisture, plough back time and so on . Hence, the real mechanism of the nutrient release of green manure deserves further study in order to make better use of green manure and increase its fertilizer efficiency in our study region.
Considering the dynamic changes of soil available nutrient content, we found that AN significantly increased with time from to in OM and NPK treatments, suggesting that the long-term soil organic matter played a major role in releasing soil AN.
The evident increase of AK in NPK treatment over time in our study, suggests that continuously applying K fertilizer would dramatically improve the soil AK supply, In addition, AP values in both OM and NPK treatments were increased greatly compared to the other three treatments during the whole experiment period.
This is consistent with many previous studies showing the accumulation of P is the most obvious and long-term manure or inorganic fertilizer application can significantly alter the amounts and proportion of labile and stable soil P pools  — .
That the OM treatment resulted in even higher AP value than NPK, also support the view that organic fertilizer is much more conducive to soil P availability rather than commercial P fertilizers in cropping systems that receive predominantly organic P amendments . In conclusion, significant differences in soil fertility of paddy soils in the red soil region of southern China among different fertilization treatments were found in our study.
However, the effect of GM application on soil fertility was not remarkable compared to CK. Hence, organic manure should be recommended to improve soil fertility in this region and K fertilizer should be simultaneously applied considering the soil K contents. Moreover, in terms of the long-term fertilizer efficiency, annual straw returning application year by year could be adopted in this trail region.
Data statistic and analysis for samples in this study. The detailed data of soil nutrient contents in different fertilization treatments for each samples in this study is shown. Analyzed the data: WD XZ.
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Analyzed the data: WD XZ. Appropriate fertilizer application is an important management practice to improve soil fertility and quality in the red soil regions of China. Results showed that the soil pH was the lowest with an average of 5. Thus, these indicated that organic manure should be recommended to improve soil fertility in this region and K fertilizer should be simultaneously applied considering the soil K contents. Considering the long-term fertilizer efficiency, our results also suggest that annual straw returning application could improve soil fertility in this trial region. In these red soil regions, Rice Oryza sativa L. Paddy soil, formed under interchange between drying and wetting rice field conditions, is considered to be the most important soil resource for the food security of China .
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Metrics details. Land degradation reduces agricultural productivity and poses a serious threat on food security status of households. Several reports that indicate lack of response to these fertilizers, which could be due to limitation of nutrients other than nitrogen and phosphorus. Therefore, the present study was initiated to evaluate the soil fertility status of ten sites in central highlands Vertisols of Ethiopia and wheat nutrient content. The physico-chemical properties of soils showed that the soils were clayey in texture, neutral to slightly alkaline pH 7.
Food insecurity is a central concern and a fundamental challenge for human welfare and economic growth in Africa. Low agricultural production, results in low incomes, poor nutrition, vulnerability to risks and lack of empowerment. Land degradation and soil fertility depletion are considered the major threats to food security and natural resource conservation in sub-Saharan Africa SSA. Investments in technology, policy and institutional reforms are needed to increase agricultural productivity to ensure food security and sustained national economies.
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Most of the time, the average person treats the soil "like dirt". In the plant-animal-soil continuum, soil is often neglected because it does not indicate stress in an obvious way. Animals and plants show physical symptoms but the soil must be looked at more carefully to monitor good health. Soil that is rich in nutrients is fertile. The expectation of growing plants as food for livestock must include the reality that plants will take nutrients out of the soil. Replacing nutrients is the basic goal of fertilization. Improper fertilization in the past has caused controversy, but the basic premise of fertilization is to replenish the soil.
These ions are present in the soil solution (water between solid soil particles) and the roots of the plant from the water and move up through the plant in xylem.
Он уходил корнями в давние времена. В эпоху Возрождения скульпторы, оставляя изъяны при обработке дорогого мрамора, заделывали их с помощью сеrа, то есть воска. Статуя без изъянов, которую не нужно было подправлять, называлась скульптурой sin cera, иными словами - без воска. С течением времени это выражение стало означать нечто честное, правдивое. Английское слово sincere, означающее все правдивое и искреннее, произошло от испанского sin сега - без воска. Этот его секрет в действительности не был никакой тайной, он просто подписывал свои письма словом Искренне.
Впервые с детских лет Беккер начал молиться. Он молился не об избавлении от смерти - в чудеса он не верил; он молился о том, чтобы женщина, от которой был так далеко, нашла в себе силы, чтобы ни на мгновение не усомнилась в его любви. Он закрыл глаза, и воспоминания хлынули бурным потоком.