Nutrient Limiting Factor and Agronomic Efficiency of Wheat in Fluvo-aquic Soil District in Northwest of Shandong Province

[Objective] This study aimed to provide basis for rational fertilizer application of wheat in fluvo-aquic soil in the northwest of Shandong Province.[Method] In this paper,the treatments of reduced N,P and K were set in order to explore the effects of fertilizer recommendation based on ASI systematic approach on wheat yield,agronomic efficiency and recovery rate of nutrients.[Result] Nitrogen was the main limiting factor for wheat production in that area,followed by phosphorus,and the third was potassium.Compared with the optimum treatment （OPT）,the reduction of N,P and K reduced the grain yield obviously,which came up to 22.4％,14.4％ and 13.4％ respectively.There were no obvious differences in grain yield among Farmer＇s Fertilization Practice （FP）,60％ OPT-N and OPT treatment.[Conclusion] Agronomic efficiency of N,P and K was 6.3,12.9 and 10 kg/kg respectively.The recovery rates of N,P and K in wheat season were 16.41％,17.27％ and 27.27％ respectively.

Experimental Study to Improve the Agronomic Efficiency of Low Grade Fine Size Rock Phosphate

Soluble phosphate fertilizers have been preferably used in plant crop production. The cost of applying conventional water soluble phosphate fertilizer is high in developing countries since their manufacturing requires importing high grade rock phosphate （RP）. As a result, the use of indigenously available low-grade RP is gaining importance globally. In this study, experiments were carried out using clayey loamy alkaline soil to evaluate the agronomic efficiency of fine sized low grade RP with inorganic nitrogen fertilizers and it was further compared with that of soluble phosphate fertilizer （di-ammonium phosphate）, Cicer arietinum was the test crops subjected to treatments of absolute control, di-ammonium phosphate and low grade RP with varying concentrations of ammonium sulphate or ammonium nitrate. The experiments were conducted during 2012-2013 in the bid to study the growth rate and the biomass of the crop. Tests were also performed to determine the residual effects of the fertilizers on the crops. The results revealed that the combined use of low grade RP and ammonium sulphate or ammonium nitrate, at 16 kg N/ha, resulted in an agronomic efficiency, in terms of biomass of plants, comparable to that of di-ammonium phosphate and was found to be a more attractive management option for resource-poor farmers.

Nitrogen Use Efficiency as Affected by Phosphorus and Potassium in Long-Term Rice and Wheat Experiments

Improving nitrogen use efficiency （NUE） and decreasing N loss are critical to sustainable agriculture. The objective of this research was to investigate the effect of various fertilization regimes on yield, NUE, N agronomic efficiency （NAE） and N loss in long-term （16- or 24-yr） experiments carried out at three rice-wheat rotation sites （Chongqing, Suining and Wuchang） in subtropical China. Three treatments were examined： sole chemical N, N＋phosphorus （NP）, and NP＋potassium （NPK） fertilizations. Grain yields at three sites were significantly increased by 9.3-81.6% （rice） and 54.5-93.8% （wheat） under NP compared with N alone, 1.7-9.8% （rice） and 0-17.6% （wheat） with NPK compared with NP. Compared to NP, NUE significantly increased for wheat at Chongqing （9.3%） and Wuchang （11.8%）, but not at Suining, China. No changes in NUE were observed in rice between NP and NPK at all three sites. The rice-wheat rotation＇s NAE was 3.3 kg kg1 higher under NPK than under NP at Chongqing, while NAE was similar for NP and NPK at Suining and Wuchang. We estimated that an uptake increase of 1.0 kg N hal would increase 40 kg rice and 30 kg wheat ha-1. Nitrogen loss/input ratios were -60, -40 or -30% under N, NP or NPK at three sites, indicating significant decrease of N loss by P or PK additions. We attribute part of the increase in NUE soil N accumulation which significantly increased by 25-55 kg ha-1 yr1 under NPK at three sites, whereas by 35 kg ha-1 yr-1 under NP at Chongqing only. This paper illustrates that apply P and K to wheat, and reduce K application to rice is an effective nutrient management strategy for both the NUE improvement and N losses reduction in China.

Agronomic and Economic Potential of Tughutu and Minjingu Phosphate Rock as Alternative Phosphorus Sources for Bean Growers

On-farm experiments were conducted in farmers' fields at 6 different sites in Western Usambara Mountains(WUM)in northern Tanzania during the 2000-2001 cropping season.The objectives were to study the effects of Tughutu(Vernonia subligera O.Hoffn)pruning in combination with Minjingu phosphate rock(MPR)or triple super phosphate(TSP)supply on the concentration of P in the tissues and seed yields of common bean,and to assess the economic returns of these different technologies to farmers.The experimental design was a randomized complete block with each of the 6 farmers' fields used as a replicate.The treatments included:control,MPR or TSP each at 26 kg P ha^(-1),Tughutu at 2.5 t ha^(-1), and Tughutu at 2.5 t ha^(-1)combined with MPR or TSP at 26 kg P ha^(-1). Addition of MPR or TSP alone significantly raised P concentration in bean shoots from 1.27 mg g^(-1)to 1.70 and 1.95 mg g^(-1)respectively.Combining MPR or TSP with Tughutu increased P concentration above the proposed deficiency level of 2 mg g^(-1).The relative agronomic effectiveness(RAE)of MPR ranged from 12.5% to 45.0%.Seed yields of common bean was markedly increased by 28%-104% from MPR or TSP supply alone,and 148%-219% from Tughutu application combined with 26 kg P ha^(-1)of MPR or TSP relative to the control.With Tughutu alone,seed yield increased by 53%. From economic analysis,the increase in seed yield with the supply of MPR or TSP combined with Tughutu translated into a significantly(P≤0.001)higher marginal rate of return and dollar profit for common bean farmers in WUM in northern Tanzania.It is concluded that Tughutu and its combined application with MPR or TSP is an appropriate integrated nutrient management strategy that may increase bean yields and dollar profit to the rural poor communities in Tanzania.

Economically Optimal Rates and Nutrients Use Efficiency Indices of Maize to the Application of Different Rates of Nutrients in Central Rift Valley of Ethiopia

The use of balanced fertilizers in adequate amount is very important to increase crop productivity and production in Ethiopia. The study was executed to quantify maize (Zea mays L.) grain yield response to different rates of nitrogen (N), phosphorus (P), potassium (K) and sulfur (S) under balanced fertilization of other nutrients. On farm trials were conducted at seven sites on 8 farmers’ fields in Negele Arsi districts, west Arsi zone of Oromia region for three consecutive cropping seasons (2014-2016). Six rates of N, P, S and eight rates of K treatments established separately for each nutrient were laid out in randomized complete block (RCB) design with three replicates per farm. Nutrient response function modelling showed that 184, 20 and 80 kg•ha−1 were the agronomic optimum rate for N, P, and K, respectively. Mean agronomic efficiency (AE) of N, P and K were recorded at the lower rates of these nutrients, application of 46, 10 and 20 kg•ha−1 N, P and K resulted in 19.1, 61.0, and 24 kg additional grain yield•kg−1 N, P and K, respectively. Also, the mean partial factor productivity (PFP) of N, P and K were 77.6, 370 and 158 kg additional grain•kg−1 applied N, P and K respectively. Economically optimal rate (EOR) of N, P and K were 48 - 114 kg•ha−1 N with CP 8 - 3.5, 12 - 20 kg•ha−1 P with CP 18 - 4.5 and 32 - 53 kg•ha−1 K with CP 8-4, from these rates net returns of US$487.23 - 143.30, US$698.16 - 498.3 and US$359.31 - 193.63 could be obtained respectively. To conclude, application of 84, 12 and 40 kg•ha−1 N, P and K could be recommended for the production of maize.

Coffee Orchard Response to Enhanced Efficiency Phosphate Fertilizer

Phosphorus (P) plays a crucial role in plant growth by aiding in the development of strong roots, promoting flower and fruit formation, and aiding in photosynthesis. Studies to improve P fertilizers efficiency in coffee orchards are necessary due to the need for better efficiency and the lack of information on enhanced efficiency P fertilizers. This study aimed to investigate the effect of MAP coated with anionic polymers (Policote) on coffee orchard development. A coffee trial was carried out in a randomized block design with three replications. The treatments, applied at coffee planting, were arranged in an incomplete factorial (2 × 4) + 1, using two P sources (MAP and Policote coated MAP), four P rates (40, 80, 120, and 160 g P2O5 plant-1) and control (without application of P fertilizer). Plant height was evaluated in the 2016/2017, 2017/2018, and 2018/2019 seasons, while coffee bean maturation, yield, and agronomic P efficiency use were evaluated in the last two seasons. P fertilization did not affect coffee bean maturation and increased coffee yield in 31-month-old plants when differences among P sources and rates were observed. Using Policote-coated P fertilizer resulted in higher yields at the same P rate, as well as similar yields at a lower P rate, compared to conventional fertilizer. Policote-coated P fertilizer can be used as an enhanced efficiency fertilizer and is an efficient way to deliver required P to plants. The target for reducing farm investment, increasing agricultural profits, preserving phosphatic rock reserves, and avoiding the overuse of phosphate fertilizer could be realized through the rational use of enhanced efficiency fertilizers.

Response of Contrasting Rice Genotypes to Zinc Sources under Saline Condition

Abiotic stresses are among the major limiting factors for plant growth and crop productivity.Among these,salinity is one of the major risk factors for plant growth and development in arid to semi-arid regions.Cultivation of salt tolerant crop genotypes is one of the imperative approaches to meet the food demand for increasing population.The current experiment was carried out to access the performance of different rice genotypes under salinity stress and Zinc(Zn)sources.Four rice genotypes were grown in a pot experiment and were exposed to salinity stress(7 dS m^(−1)),and Zn(15 mg kg^(-1)soil)was applied from two sources,ZnSO4 and Zn-EDTA.A control of both salinity and Zn was kept for comparison.Results showed that based on the biomass accumulation and K^(+)/Na^(+)ratio,KSK-133 and BAS-198 emerged as salt tolerant and salt sensitive,respectively.Similarly,based on the Zn concentration,BAS-2000 was reported as Zn-in-efficient while IR-6 was a Zn-efficient genotype.Our results also revealed that plant growth,relative water content(RWC),physiological attributes including chlorophyll contents,ionic concentrations in straw and grains of all rice genotypes were decreased under salinity stress.However,salt tolerant and Zn-in-efficient rice genotypes showed significantly higher shoot K^(+)and Zn concentrations under saline conditions.Zinc application significantly alleviates the harmful effects of salinity by improving morpho-physiological attributes and enhancing antioxidant enzyme activities,and the uptake of K and Zn.The beneficial effect of Zn was more pronounced in salt-tolerant and Zn in-efficient rice genotypes as compared with salt-sensitive and Zn-efficient genotypes.In sum,our results confirmed that Zn application increased overall plant’s performance under saline conditions,particularly in Zn in-efficient and tolerant genotypes as compared with salt-sensitive and Zn efficient rice genotypes.

Optimizing N fertilizer use for sesame under rain fed and irrigation conditions in Northern Ethiopia

Inappropriate use of fertilizers is one of the major production constraints in sesame. Studies on N fertilizer optimization on sesame were conducted at Humera Agricultural Research Center(Hu ARC) under rain fed and irrigation conditions. Thirteen(13) N doses were evaluated in a Randomized Complete Block Design(RCBD)during 2016–2018 for rainfed conditions and 2017 to 2019 for irrigation conditions. The study was conducted with objective to optimize N fertilizer use for sesame. In the rainfed condition, the results demonstrated a prolonged duration to reach 50% flowering with higher nitrogen(N) application rates. The application of 52.5–110kg N ha^(-1) resulted in significantly higher seed yield, while lower(18 kg N ha^(-1)) and higher(156 kg N ha^(-1)) doses of N led to reduced seed yield. Under irrigation conditions, superior seed weights and maximum seed yield were observed at 64 and 75 kg N ha^(-1), whereas lower N doses resulted in diminished seed yield. The agronomic efficiency of N fertilizer(N-AE) was found to be highest at the rate of 64 kg N ha^(-1) under both growing conditions.The partial budget analysis revealed that applying 64 kg N ha^(-1) for rainfed cultivation and between 64 and 75 kg N ha^(-1) for irrigated sesame production yielded greater net profit, MRR, and residual ranking. Therefore, it is recommended to apply a rate of 64 kg N ha^(-1) for rainfed sesame cultivation and between 64 up to 75 kg N ha^(-1) for the irrigated sesame inorder to increase the productivity of this crop.

Optimizing Fertilizer Use by Smallholder Farmers and Economic Returns to Maize in Semi-arid Niger

Maize （Zea mays L.） is an important food crop in Niger, but low and irregular rainfall combined with sandy soils having low fertility level limit productivity. A two-year study was conducted at Institut National de Recherche Agronomique du Niger （INRAN） stations in Tarna/Maradi and Bengou/Gaya in 2014 and 2015 in order to evaluate maize agronomic and economic fertilizer use efficiency. The experimental design was a randomised complete block design （RCBD） with three replications. Results indicate higher effect of fertilizer in 2015 compared to 2014. At low N rates 20 kg N/ha and 40 kg N/ha, application of 20 kg P/ha increased maize grain yield across locations and years. The highest agronomic efficiency of N （AEN） was recorded with 60 kg N/ha in 2015 at Bengou and Tarna with 9.65 kg and 14.05 kg grain yield per kg of applied N, respectively. At Tarna, the low N rates of 20 kg N/ha and 40 kg N/ha recorded important AEN of more than 12 kg yield increases per kg of applied N. The highest rainfall use efficiency （RUE） of 6.13 kg/year/mm was obtained with application of 80 kg/ha N, 0 kg/ha P and 40 kg/ha N, 20 kg/ha P in 2015 at Tarna. Without P, the highest value cost ratio （VCR） value of 4.31 was recorded at Tarna in 2015 with 60 kg/ha N, and the lowest value of 0.08 at Bengou in 2014 with 20 kg/ha N. Based on VCR and RUE derived from this study, the optimal fertilizer recommendation for maize in the semi-arid conditions of Niger could be 40 kg/ha N, 20 kg/ha P and 0 kg/ha K.

Assessment of Fertilising Properties of a Solid Digestate in Comparison with Undigested Cattle Slurry Applied to an Acidic Soil

The use of digestates or cattle slurries as fertilisers could contribute to the recycling of nutrients and organic matter, thus meeting the goals of the circular economy in agriculture. This work aims at evaluating the fertilising properties of a solid digestate (DG) in comparison with undigested cattle slurry (CS) and mineral fertilisation (MF). The experiment was performed in pots with ryegrass (Lolium multiflorum Lam.) grown in an acidic soil during a 163 days crop cycle. The results showed that throughout the crop cycle neither DG nor CS increased soil organic matter. DG significantly increased (P < 0.001) the sum of the soil exchangeable bases and soil P availability compared with CS or MF. Also, DG significantly increased (P < 0.05) the apparent P recovery of ryegrass (43%) compared with MF (27%). In the first cut, the ryegrass yield was higher in DG and CS than in MF, decreasing in the second and third cuts as a consequence of a decrease in N availability. Nevertheless, the fertilisation with DG or CS could replace the half amount of mineral N fertilisation, without a significant decrease in the ryegrass forage production. In addition, DG enables greater efficiency in the use of P than CS or MF.

Agronomic evaluation of Herbaspirillum seropedicae strain ZAE94 as an inoculant to improve maize yield in Brazil

Diazotrophic bacteria applied as a seed inoculant can improve the grain yield of several crops including maize. The current study aimed to test the agronomic efficiency and contribution of biological nitrogen fixation(BNF) of the endophytic diazotroph Herbaspirillum seropedicae strain ZAE94 to maize under field conditions. Eighteen field assays were conducted in four different locations during consecutive years on two hybrids and two varieties of maize in a random block design with four replicates using a peat-based inoculant. The inoculant containing the ZAE94 strain was applied without nitrogen(N)fertilization or with 40 kg N ha^(-1) and was compared to the application of 40 and 80 kg N ha^(-1) without inoculation. Crop productivity and N accumulation in the grain were evaluated in addition to ^(15)N natural abundance(δ^(15)N) to evaluate BNF in the treatments without N fertilization. Fertilization at 40 kg N ha^(-1) plus bacterial inoculation produced crop yields similar to the treatment with 80 kg N ha^(-1) and increased grain N content, especially in the off-season with 40 kg N ha^(-1). The inoculation treatments showed lower δ^(15)N values than the non-inoculated treatments, which was most evident in the off-season. The BNF contributed about 30% of N accumulated in plants inoculated with ZAE94. On average, 64% of the N fertilized plots showed an increase of the parameters evaluated in the inoculated treatments, compared with the control. Inoculation also increased root length, root volume, and leaf area, and these parameters were positively correlated with plant weight using a hydroponic assay. This study revealed that the application of H. seropedicae inoculant increased the amount of N in plants owing to BNF, and there is a better chance of yield response to inoculation under low N fertilizer application in the off-season.

Increasing phosphorus fertilizer value of recycled iron phosphates by prolonged flooding and organic matter addition

Iron(Fe)minerals are commonly used to remove phosphorus(P)from waste streams,producing P-loaded Fe(Ⅲ)oxides or Fe(Ⅱ)phosphate minerals(e.g.,vivianite).These minerals may be used as fertilizers to enhance P circularity if solubilized in soil.Here,we tested the P fertilizer value of recycled Fe phosphates(FePs)in a pot trial and in an incubation experiment,hypothesizing that P release from FePs is possible under Fe(Ⅲ)-reducing conditions.First,a pot trial was set up with rice(Oryza sativa)in all combinations of soil flooding or not,three P-deficient soils(acid,neutral,and calcareous),and six FePs(three Fe(Ⅲ)Ps and three Fe(Ⅱ)Ps)referenced to triple superphosphate(TSP)or zero amendments.Shoot P uptake responded to TSP application in all treatments but only marginally to FePs.The redox potential did not decrease to-200 mV by flooding for a brief period(13 d)during the pot trial.A longer incubation experiment(60 d)was performed,including a treatment of glutamate addition to stimulate reductive conditions,and P availability was assessed with CaCl_(2)extraction of soils.Glutamate addition and/or longer incubation lowered soil redox potential to<-100 mV.On the longer term,Fe(Ⅲ)minerals released P,and adequate P was reached in the calcareous soil and in the neutral soil amended with Fe(Ⅲ)P-sludge.It can be concluded that prolonged soil flooding and organic matter addition can enhance the P fertilizer efficiency of FePs.Additionally,application of FeP in powder form may enhance P availability.