Use Efficiency Of Rice Research Articles

Optimizing chlorophyll meter (SPAD) reading to allow efficient nitrogen use in rice and wheat under rice-wheat cropping system in eastern India

ABSTRACT Conventional agricultural practices that rely heavily on blanket fertilizer recommendation, eventually leading to deteriorated partial factor productivity and N use efficiency. We investigated the effect of SPAD-based N-management on productivity and N use efficiency of rice and wheat in eastern India. Here, in the experiment three SPAD thresholds (34, 36 and 38 in rice and 38, 40 and 42 in wheat) using three N levels (15, 25 and 35 kg N ha−1) in split were incorporated as real-time N management (RTNM), one fixed-time N management (FTNM), farmers’ fertilizer practice (FFP) and control (No fertilizer) were introduced in wet and dry seasons for rice and wheat, respectively, during the years 2010 to 2012. Topdressing with 25 kg N ha−1 at medium SPAD (S36 in rice and S40 in wheat) increased soil N availability, leaf N content and grain yield of rice (5215 kg ha−1) and wheat (4483 kg ha−1) over the grain yield recorded under a low rate of N topdressing at low SPAD. While saving 33.3% N in rice and 18.8% N in wheat, the agronomic N use efficiency (58.5% in both rice and wheat) and nitrogen recovery efficiency (32.2% in rice and 15.1% in wheat) can be increased when compared with conventional FTNM. The SPAD-based management strategy showed great promise in efficient management of N fertilizer, and we estimated the optimal SPAD threshold for rice and wheat as 37.5 and 41.8, respectively.

Improvement of nutrient use efficiency in rice: current toolbox and future perspectives.

Modern agriculture relies heavily on chemical fertilizers, especially in terms of cereal production. The excess application of fertilizers not only increases production cost, but also causes severe environmental problems. As one of the major cereal crops, rice (Oryza sativa L.) provides the staple food for nearly half of population worldwide, especially in developing countries. Therefore, improving rice yield is always the priority for rice breeding. Macronutrients, especially nitrogen (N) and phosphorus (P), are two most important players for the grain yield of rice. However, with economic development and improved living standard, improving nutritional quality such as micronutrient contents in grains has become a new goal in order to solve the "hidden hunger." Micronutrients, such as iron (Fe), zinc (Zn), and selenium (Se), are critical nutritional elements for human health. Therefore, breeding the rice varieties with improved nutrient use efficiency (NUE) is thought to be one of the most feasible ways to increase both grain yield and nutritional quality with limited fertilizer input. In this review, we summarized the progresses in molecular dissection of genes for NUE by reverse genetics on macronutrients (N and P) and micronutrients (Fe, Zn, and Se), exploring natural variations for improving NUE in rice; and also, the current genetic toolbox and future perspectives for improving rice NUE are discussed.

Response of split application of nitrogen on yield and nitrogen use efficiency of rice under high rainfall area of Andaman & Nicobar islands

A Field experiment was carried out at farmer's field of Port Mout village of South Andaman district of A & N Islands during Kharif season of 2015 under a National Network Project National Innovation on Climate Resilient Agriculture to study the response of split application of nitrogen on yield and nitrogen use efficiency of rice. The results revealed that application of four split of 15 per cent at 10 DAT, 35 per cent at active tillering, 25 per cent at panicle initiation and 25 per cent at flowering stage recorded 1.60 and 2.59 q//ha of additional higher grain and straw yield as compared to other four split application of nitrogen i.e. 25 per cent at basal, 25 per cent at active tillering, 25 per cent at panicle initiation and 25 per cent at flowering stage. Net return of ₹ 27430/ha with B: C ratio of 2.02 and higher agronomic efficiency, partial factor productivity, physiological use efficiency and NPK uptake were obtained with application of nitrogen in four split of 15 per cent at 10 DAT, 35 per cent at active tillering, 25 per cent at panicle initiation and 25 per cent at flowering stage as compared to other treatments.

Effects of the amount of ammonium sulfate and nitrification inhibitor on nitrogen use efficiency of rice cultivated under drip irrigation in upland field

Effects of the amount of ammonium sulfate and nitrification inhibitor on nitrogen use efficiency of rice cultivated under drip irrigation in upland field

Effects of the amount of nitrogen fertilizer and dicyanodiamide on dry matter production and radiation use efficiency in rice cultivated under drip irrigation in upland field

Effects of the amount of nitrogen fertilizer and dicyanodiamide on dry matter production and radiation use efficiency in rice cultivated under drip irrigation in upland field

Optimizing integrative cultivation management improves grain quality while increasing yield and nitrogen use efficiency in rice

A major challenge in rice (Oryza sativa L.) production is to cope with increasing grain yield and fertilizer use efficiency without compromising grain quality. This study was designed to determine if optimizing integrative cultivation management in rice could improve grain quality while increase yield and nitrogen use efficiency (NUE). An indica-japonica hybrid rice cultivar and a japonica rice cultivar were grown in the field, with five cultivation managements including no N application (0 N), local farmer's practice (LFP), and three optimizing integrative cultivation managements, reducing N rate and increasing plant density (ND), ND+alternate wetting and moderate soil drying irrigation (NDW), and NDW+applying rapeseed cake fertilizer (NDWR). The results showed that the optimizing integrative cultivation managements could not only increase grain yield, but also enhance NUE compared to LFP. Compared to LFP, NDWR significantly increased brown, milled, head milled rice rate, ratio of the kernel length to breadth and breakdown value of starch, whereas decreased amylose content, gel consistency, prolamin content, setback value, percentage of chalky kernels, and chalkiness. The three optimizing integrative cultivation managements increased contents of total proteins, albumin and glutelin, activities of the key enzymes involved in the sucrose-starch conversion in grains, root oxidation activity, and malic and succinic acid concentrations in root exudates during the grain-filling period. The results suggested that optimizing integrative cultivation managements could improve grain quality meanwhile increase grain yield and NUE by enhancing physiological activities of rice plants.

Genome-wide associated study identifies NAC42-activated nitrate transporter conferring high nitrogen use efficiency in rice

Over-application of nitrogen fertilizer in fields has had a negative impact on both environment and human health. Domesticated rice varieties with high nitrogen use efficiency (NUE) reduce fertilizer for sustainable agriculture. Here, we perform genome-wide association analysis of a diverse rice population displaying extreme nitrogen-related phenotypes over three successive years in the field, and identify an elite haplotype of nitrate transporter OsNPF6.1HapB that enhances nitrate uptake and confers high NUE by increasing yield under low nitrogen supply. OsNPF6.1HapB differs in both the protein and promoter element with natural variations, which are differentially trans-activated by OsNAC42, a NUE-related transcription factor. The rare natural allele OsNPF6.1HapB, derived from variation in wild rice and selected for enhancing both NUE and yield, has been lost in 90.3% of rice varieties due to the increased application of fertilizer. Our discovery highlights this NAC42-NPF6.1 signaling cascade as a strategy for high NUE and yield breeding in rice.

Molecular control and genetic improvement of phosphorus use efficiency in rice

Phosphorus (P) is an essential nutrient for plant growth and development. Phosphate (Pi) fertilizer supply is an effective way to improve crop yield. However, generally, less than 25% of the applied Pi is taken up by crops. Therefore, it is urgent to improve crop P use efficiency. The overall P use efficiency includes processes of P acquisition from soil, translocation from root to shoot, allocation, utilization, and remobilization within plant; each process can be developmentally and environmentally regulated. In this review, we summarize recent studies on molecular mechanisms and regulatory pathways involved in rice root Pi acquisition, Pi transportation from root to shoot, and allocation and remobilization of Pi within plant tissues. The possible strategies for improving crop P use efficiency are also discussed.

Organic Manure Coupled with Inorganic Fertilizer: An Approach for the Sustainable Production of Rice by Improving Soil Properties and Nitrogen Use Efficiency

The current farming system is heavily reliant on chemical fertilizers, which negatively affect soil health, the environment, and crop productivity. Improving crop production on a sustainable basis is a challenging issue in the present agricultural system. To address this issue, we assumed that the combined use of organic manure and inorganic nitrogen (N) fertilizers can improve rice grain yield and soil properties without the expense of the environment. This study explores the combined effects of cattle manure (CM), poultry manure (PM), and chemical fertilizer (CF) on soil properties, rice growth, physiology, and grain yield and quality. Six treatments in the following combinations were included: T1—no N fertilizer; T2—100% CF; T3—60% CM + 40% CF; T4—30% CM + 70% CF; T5—60% PM + 40% CF; and T6—30% PM + 70% CF. Results showed that across the seasons, treatment T6 increased the net photosynthesis rate, total biomass, grain yield, and amylose content by 23%, 90%, 95%, and 10%, respectively, compared with control. This increment in net photosynthetic rate and growth was the result of 24%, 14%, 19%, and 20% higher total root length, root surface area, root volume, and root diameter, respectively. Improvements in these attributes further enhanced the grain yield and nitrogen use efficiency of rice. No significant difference between T4 and T6 was observed. The correlation analysis also confirmed that root morphological traits were positively correlated with grain yield, N uptake, and biomass accumulation. Similarly, improvement in grain yield and NUE was also associated with improved soil properties, i.e., bulk density, soil porosity, soil organic carbon, and total N under combined organic and inorganic N fertilizers treatment. Conclusively, the integration of 30% N from PM or CM with 70% N from CF (urea) is a promising option not only for higher grain yield and quality of rice but also for improved soil health. This study provides a sustainable nutrient management strategy to improve crop yield with high nutrient use efficiency.

Effects of methodical nitrogen-water distribution management on water and nitrogen use efficiency of rice

Effects of methodical nitrogen-water distribution management on water and nitrogen use efficiency of rice

OsATG8c-Mediated Increased Autophagy Regulates the Yield and Nitrogen Use Efficiency in Rice.

Autophagy, a conserved pathway in eukaryotes, degrades and recycles cellular components, thus playing an important role in nitrogen (N) remobilization. N plays an important role in the growth and development of plants, which also affects plant yield and quality. In this research, it was found that the transcriptional level of a core autophagy gene of rice (Oryza sativa), OsATG8c, was increased during N starvation conditions. It was found that the overexpression of OsATG8c significantly enhanced the activity of autophagy and that the number of autophagosomes, dwarfed the plant height and increased the effective tillers’ number and yield. The nitrogen uptake efficiency (NUpE) and nitrogen use efficiency (NUE) significantly increased in the transgenic rice under both optimal and suboptimal N conditions. Based on our results, OsATG8c is considered to be a good candidate gene for increasing NUE, especially under suboptimal field conditions.

Floating duckweed mitigated ammonia volatilization and increased grain yield and nitrogen use efficiency of rice in biochar amended paddy soils

Biochar (BC) potentially accelerates ammonia (NH3) volatilization from rice paddy soils. In this regard, however, application the floating duckweed (FDW) to biochar-amended soil to control the NH3 volatilization is not studied up-to-date. Therefore, the impacts of BC application with and without FDW on the NH3 and nitrous oxide (N2O) emissions, NUE and rice grain yield were evaluated in a soil columns experiment. We repacked soil columns with Hydragric Anthrosol and Haplic Acrisol treated in triplicates with Urea, Urea+BC and Urea+BC+FDW. Total NH3 losses from Hydragric Anthrosol and Haplic Acrisol were 15.2-33.2 kg N ha-1 and 19.6-39.7 kg N ha-1, respectively. Urea+BC treatment recorded 25.6-43.7% higher (p < 0.05) NH3 losses than Urea treatment, attributing to higher pH value of floodwater. Floating duckweed decreased soil pH and therefore significantly reduced (p < 0.05) the NH3 volatilizations from the two soils by 50.6-54.2% over Urea+BC and by 34.2-38.0% over Urea treatment. Total N2O emissions from Hydragric Anthrosol and Haplic Acrisol were 1.19-3.42 kg N ha-1 and 0.67-2.08 kg N ha-1, respectively. Urea+BC treatment increased N2O emissions by 58.8-68.7% and Urea+BC+FDW treatment further increased N2O emission by 187.4-210.4% over Urea treatment. Higher ammonium content of the topsoil, explained the N2O increases in the Urea+BC and Urea+BC+FDW treatments. Urea+BC slightly reduced the rice grain yield and NUE, while the Urea+BC+FDW promoted both rice yield and NUE. Our data indicate that co-application of FDW along with BC in paddy soil could mitigate the NH3 volatilization and enhance the rice grain yield and NUE.

Effect of Zinc on Growth, Yield and Zinc Use Efficiency of Rice in Rice–Wheat Cropping System

A four year rice-wheat cropping (2012-15) was developed on Nursery Jhilli area of Rajendra Agricultural University, Pusa, Bihar, where zinc applied in four different doses (2.5, 5.0, 7.5 and 10.0 kg ha-1) and 3 modes of application under rice – wheat cropping system, to investigate the effect of different doses of Zn and modes of application on rice growth parameters, yield and Zn use efficiency. Results reveled that among the different growth and yield attributing characteristics of rice the highest of number of tillers m-2, number of productive tillers m-2 and number of filled grain panicle-1 were observed in 7.5 kg Zn ha-1 at alternate year applied plot. Root weight were highest in 7.5 kg Zn ha-1 every year applied plot. The grain and straw yield data clearly indicated that application of zinc significantly increased both yields. The highest grain yield was found in 5 kg Zn ha-1 applied every year (40.20 q ha-1) and 7.5 kg Zn ha-1 in initial year application was the lowest dose for optimum rice grain yield in the fourth year. Highest Agronomic Efficiency was found in 7.5 kg Zn ha-1 (101.33 kg grain/ kg Zn) and the order of apparent Zn recovery efficiency was in the order of, 2.5 kg Zn, alternate year (3.72%) &gt; 2.5 kg Zn, initial year (3.70%) &gt; 7.5 kg Zn, every year (3.61%) &gt; 2.5 kg Zn, every year (3.58%). A suitable dose (5 kg Zn ha-1) of Zn found more efficient in term of yield and recovery efficiency than high or low doses, this can be helpful to farming communities for better earning and reduce excessive application.

Influence of integrated in-soil zinc application and organic fertilization on yield, nitrogen uptake and nitrogen use efficiency of rice

Zinc deficiency is the most widespread challenge in rice cultivation, as well as the shortage of agricultural soil in organic matter, especially in Egypt. So it was experimentation of compost treatment (12 t ha-1) and in-soil zinc applications at three rates (0, 8 and 16 kg ZnSO4.7H2O ha-1), on growth, yield, total nitrogen uptake, agronomic nitrogen efficiency and nitrogen recovery efficiency of rice crop (Oryza sativa), variety Giza 178. Using organic fertilization as compost has recorded the highest values of plant height, dray weight, grain yield, straw yield, total nitrogen uptake, agronomic nitrogen efficiency and nitrogen recovery efficiency. In addition, in-soil zinc application rates are increasingly applied to the previous parameters. The increase in rice grain and straw yield by applying 12 t compost ha-1 was 13.4% and 7.14%, respectively, while applying 16 kg ZnSO4.7H2O ha-1 increased the rice grain yield by 12.31% and 17.55% increase in rice straw yield. Remarkable results have been registered when examining 16 kg Zn ha-1 with 12 t compost ha-1 on total nitrogen uptake and nitrogen recovery efficiency have been enhanced even under saline soil conditions.

The Effect of Dry Cultivation on Yield, Water, and Iron Use Efficiency of Rice

Core Ideas Dry cultivation reduces yield, except for the absence of significant differences between plastic film mulching cultivation and continuously flooded in paddy rice.Dry cultivation increases Fe use efficiency and water use efficiency.The Fe per unit mass of rice grains in upland rice is richer than that in paddy rice.Dry cultivation is a good water conservation cultivation method in arid and semi‐arid regions with unstable irrigation sources while temperature is favorable to rice growth. Iron is not only an essential trace element for plant growth and development, but also an indispensable trace element for humans. The objective of this study was to investigate the Fe absorption and utilization, water use efficiency (WUE) and grain yield difference between upland rice (Oryza sativa L.) cultivar Zhonghan 3 (japonica) and paddy rice cultivar Wuxiangjing 99‐8 (japonica) which were grown on the farm of the Yangzhou University under three cultivation patterns of continuously flooded condition (CF, control), plastic film mulching cultivation (PFMC), and bare cultivation (BC) under non‐flooded conditions. Compared with the CF, the grain yield was significantly lower under the PFMC for upland rice, but no significant difference was found for paddy rice, and grain yield was significantly reduced under BC for both upland rice and paddy rice. Dry cultivation lowered the Fe concentration in the rice plants and grain under the PFMC and the BC, and lowered the amount of Fe absorption in aboveground plants. Whereas, Fe use efficiency and WUE were all higher with dry cultivation. Compared with paddy rice, the Fe concentration in the whole root system of upland rice was 39.5% lower, but that in the roots was 11.3% higher at heading stage, and in the aboveground plants and rice flour was 3.4 to 11.1% higher at heading and maturity stages. The results indicate that dry cultivation is a good water conservation cultivation method in arid and semiarid regions with unstable irrigation sources while temperature is favorable to rice growth, such as in Southeast China.

Nitrogen nutrition and use efficiency in rice as influenced by crop establishment methods, cyanobacterial and phosphate solubilizing bacterial consortia and zinc fertilization

ABSTRACTA field experiment was conducted at the ICAR-Indian Agricultural Research Institute, New Delhi during wet season of 2013 and 2014, involving three crop establishment methods (CEMs) viz. puddled transplanted rice (PTR), system of rice intensification (SRI), and aerobic rice system (ARS). Three rates of nitrogen (N) and phosphorus (P) application (0%, 75%, and 100% of recommended dose of N and P) (RDN) (120 kg N ha–1 and 25.8 kg P ha–1) and two sources of N and P (fertilizer and cyanobacterial-bacterial inoculation) were tested with and without zinc (Zn) fertilization in all CEMs. The concentration of N in PTR and SRI was significantly higher than ARS with higher uptake of 10.3 and 11.1 kg ha–1 in PTR and SRI over ARS. Treatment with 100% RDN led to significantly higher N availability and uptake than 75% RDN and absolute control, i.e. 14.5 and 32.0 kg ha–1, respectively. Application of Anabaena-Pseudomonas biofilm formulation (MC2) in conjunction with 75% RDN increased total uptake of N by 12.7 kg ha–1 compared to 75% RDN only. A positive correlation was found between N concentration and acetylene reductase activity at 70 days after sowing (DAS) (R2 = 0.52) and 100 DAS (R2 = 0.38) based on mean of 2 years study. Zn fertilization significantly increased N concentration in rice straw and milled rice irrespective of the crop establishment methods. Our study signifies the importance of microbial inoculation, optimal N fertilization along with SRI and PTR as more effective crop establishment methods for deriving greater benefits in terms of N nutrition in rice.

An Integrated Analysis of the Rice Transcriptome and Metabolome Reveals Differential Regulation of Carbon and Nitrogen Metabolism in Response to Nitrogen Availability.

Nitrogen (N) is an extremely important macronutrient for plant growth and development. It is the main limiting factor in most agricultural production. However, it is well known that the nitrogen use efficiency (NUE) of rice gradually decreases with the increase of the nitrogen application rate. In order to clarify the underlying metabolic and molecular mechanisms of this phenomenon, we performed an integrated analysis of the rice transcriptome and metabolome. Both differentially expressed genes (DEGs) and metabolite Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis indicated that carbon and nitrogen metabolism is significantly affected by nitrogen availability. Further analysis of carbon and nitrogen metabolism changes in rice under different nitrogen availability showed that high N inhibits nitrogen assimilation and aromatic metabolism pathways by regulating carbon metabolism pathways such as the tricarboxylic acid (TCA) cycle and the pentose phosphate pathway (PPP). Under low nitrogen, the TCA cycle is promoted to produce more energy and α-ketoglutarate, thereby enhancing nitrogen transport and assimilation. PPP is also inhibited by low N, which may be consistent with the lower NADPH demand under low nitrogen. Additionally, we performed a co-expression network analysis of genes and metabolites related to carbon and nitrogen metabolism. In total, 15 genes were identified as hub genes. In summary, this study reveals the influence of nitrogen levels on the regulation mechanisms for carbon and nitrogen metabolism in rice and provides new insights into coordinating carbon and nitrogen metabolism and improving nitrogen use efficiency in rice.

Reducing Ammonia Volatilization and Improving Nitrogen use Efficiency of Rice at Different Depths of Urea Supergranule Application

ABSTRACTAn experiment was conducted to determine the depth of urea supergranule (USG) application that reduces ammonia (NH3) volatilization and improves nitrogen use efficiency of rice. Canne, Voudou, Akuse, and Bumbi series were used. Treatments involved surface application of prilled urea (PU), USG applied at 0, 4, 8, 12 and 16 cm depths and a control. Rice variety IR-841 was grown up to maturity. Closed chamber device was used to trap NH3. Results indicated that the highest mean NH3 loss occurred in Bumbi series (13.67%) while the lowest was Canne series (8.16%). USG applied at 0 cm resulted in the highest NH3 loss (37.2%). NH3 volatilization decreased with increasing depth of USG application. The highest grain yields were obtained when USG was applied at 4 and 8 cm. In Canne series, the highest agronomic use efficiency (AE) of N (57 g g−1) was obtained with USG applied either at 8 or 12 cm while the highest recovery efficiency (RE) (84%) occurred at 8 cm. In Akuse series, the highest AE (55 g g−1) and RE (78%) were obtained when USG was placed at 8 cm. In Voudou and Bumbi series, the highest AE (45 and 48 g g−1 respectively) and RE (64%) were obtained with USG deep placed at 4 cm. The results therefore suggested different specific depths of USG application to reduce ammonia loss and improve nitrogen use efficiency.

Mechanized transplanting with side deep fertilization increases yield and nitrogen use efficiency of rice in Eastern China

The application of nitrogen (N) fertilizer deep in soil at the same time as mechanical transplanting of rice seedlings is an effective alternative to conventional broadcasting of fertilizer, but its effects on yields and profitability have not been analysed in detail. Here, we analysed the effects of a side deep application of N fertilizer at transplanting on the N uptake, N use efficiency (NUE), grain yield, and economic profitability of two rice (Oryza sativa L.) cultivars; Yongxian15 (early season) and Yongyou1540 (middle/late season). In the field experiments, two types of N fertilizer (urea (U) and controlled-release urea (CRU)) were surface broadcasted manually (B) or mechanically fertilized at 5.5 ± 0.5 cm soil depth (M) (UB, UM, and CRUM treatments, respectively). The blank control had no N fertilizer (N0). Each N-fertilizer treatment had similar effects on N uptake, grain yield, NUE, and economic profitability in the early, middle, and late seasons. Compared with manually applied fertilizer, mechanically applied fertilizer increased grain yield and NUE in both cultivars. In Yongxian15 and Yongyou1540, the mechanical side deep application of N-fertilizer increased the N recovery efficiency by 62.50–91.57% and 24.38–64.24%, respectively, the N agronomy efficiency by 33.65–63.14% and 22.64–44.70%, respectively; and the grain yield by 6.30–11.64% and 6.23–13.11%, respectively. The CRUM treatments had the highest benefit–cost ratio because of high gross returns and low fertilization costs. The mechanized side deep application of N fertilizer can increase the efficiency and profitability of rice production.

Effects of combined application of pig manure with urea on grain yield and nitrogen utilization efficiency in rice-wheat rotation system

To examine the effects of pig manure application on dry matter production, nitrogen accumulation and distribution, grain yield and nitrogen use efficiency of rice and wheat, the field trial was conducted with wheat 863 and rice 498. Fertilization treatments consisted of seven rates of organic manure supply: control (CK, no chemical nitrogen fertilizer, no pig manure), conventional fertilizing (T1, no pig manure), 2500 kg·hm-2 pig manure with 75% conventional fertilizing (T2), 5000 kg·hm-2 pig manure with 50% conventional fertilizing (T3), 10000 kg·hm-2 pig manure (T4), 15000 kg·hm-2 pig manure (T5) and 20000 kg·hm-2 pig manure (T6). Combined application of pig manure with chemical fertilizer promoted dry matter accumulation of rice and wheat throughout the growing season. At the maturity stage of rice and wheat, the highest aboveground dry matter accumulation presented under highest pig manure input (T6). The dry matter accumulation and nitrogen distribution were enriched in stem or leaf. The dry matter accumulation and nitrogen distribution rate in grain at T6 was significantly lower than T2 treatment. The high-est nitrogen fertilizer partial productivity, fertilizer agronomic efficiency and grain yield of rice pre-sented at T3 treatment, which increased by 11.4%, 55.4%, 11.4% than that of conventional chemical fertilizer treatment, respectively. These vaules for wheat were at T2, which was 14.0%, 29.1%, 14.0% higher than that of conventional fertilizer treatment, respectively. The combined application of pig manure with appropriate rates of chemical fertilizer (T2 and T3) could promote dry matter accumulation, the migration of nitrogen to grains, the increase of yield and the nitrogen use efficiency. Too much pig manure input (15000-20000 kg·hm-2) could lead to excessive supply of nitrogen for crops. In this case, the transportation of dry matter to economic organs would be blocked and the nitrogen enriched to stem. The late-maturing phenomenon occurred, resulting in significant decrease of grain yield.