Phosphorus (P) availability is a critical factor influencing plant growth, particularly in highly weathered tropical and subtropical soils where mineral and organic P sources often exhibit low absorption efficiency. In response to soil low P availability, plants typically undergo physiological and biochemical adaptation, including reduced photosynthetic rates, increased root/shoot ratio, and alterations in the root system. This study aimed to assess changes in the maize root system and their relationship with P absorption and utilization efficiency under field conditions. The experimental design comprised three treatments: pig slurry, mineral fertilizer, and a control with no fertilizer, arranged in a randomized block design with four replications. Key morphological parameters were analyzed at the vegetative (V8) and flowering (R1) phenological stages, alongside physiological and chemical assessments of the aboveground plant parts. Plants grown in soil with a history of pig slurry application had the lowest morphological root parameters, yet demonstrated higher P absorption efficiency, grain yield, and dry matter production. The application of pig slurry and mineral fertilizers increased P and potassium (K) levels in the soil, photosynthetic rates, and dry matter production. These findings underscore the complex interplay between root morphology and nutrient absorption, offering insights into optimizing fertilizer strategies for maize cultivation in low-P availability soils.

Understanding the chemical and biological processes in the corn rhizosphere that govern nitrogen (N) availability can improve fertilizer management strategies, such as pig slurry (PS) application, in no-till systems on subtropical soils. This study aimed to assess changes in soil chemical properties and microbial activity associated with N availability in the rhizosphere of corn grown in an area with a 17-year history of PS and mineral fertilizer (MF) use. The study was conducted in a long-term field experiment (2004-2021) in southern Brazil, with treatments consisting of PS, MF, and a no-fertilizer control. Rhizospheric and non-rhizospheric (bulk) soils were sampled during the 2019/20 and 2020/21 growing seasons. Soil samples were analyzed for urease and (3-glucosidase activities, microbial biomass carbon (C) and nitrogen (N), total organic carbon (TOC), total N (TN), and pH. Long-term PS application enhanced N availability and improved soil quality in the rhizosphere compared with MF alone. PS increased TOC and enzyme activity, particularly (3-glucosidase activity in rhizospheric soil, which may facilitate N release to plants. These improvements were associated with increased crop yiels, despite rhizospheric soil pH remaining similar to that of the control treatment. PS also elevated microbial biomass C and N and urease activity, especially in the rhizosphere, although these responses were not directly associated with higher yields. Nevertheless, enhanced N availability in the rhizosphere was evident. These findings suggest that PS application may be a viable strategy for improving soil microbial activity and nutrient cycling in corn production systems under long-term no-till management.

Hops are cultivated in fertile soils in temperate climates. However, have been cultivated in countries in subtropical and tropical regions, where the soils have low availability of nitrogen (N) to plants. Therefore, N fertilization is necessary. However, hop cultivars may have different kinetic parameters of absorption, which may provide greater or lesser efficiency in the absorption of N forms. The study aimed to evaluate the kinetic parameters related to the absorption of mineral N forms in hop cultivars. Cultivars 'Cascade', 'Chinook', and 'Columbus' after 21 days of cultivation in a 50% Hoagland solution were transferred to a CaSO4 solution (0.01 mol L-1) for 10 days, in order to deplete their internal reserves. Photosynthetic and morphological variables, total N concentration in cultivar organs, and NO3- and NH4+ concentrations in the solution was analyzed. Cultivar 'Columbus' showed higher fresh matter production potential, good photosynthetic performance, higher maximum absorption rate values for NO3- and NH4+, and higher NO3- influx values, indicating that it is suitable for cultivation in substrates with high N availability. Cultivar 'Chinook' had the greatest photosynthetic potential and, therefore, it can show rapid growth and high productivity and lower concentration minimum value, indicating that it can perform well in environments with low N availability. 'Cascade' showed higher root growth potential, higher tissue N concentration values in different parts, and higher NH4+ influx values, indicating that it is suitable for soils with high NH4+ availability. Kinetic parameters can be used to select genotypes that are more efficient in nutrient uptake.

Mycorrhizal inoculants can contribute to the development of corn crops by improving crop productivity. In this sense, the objective of this study was to evaluate the effects of a mycorrhizal inoculant on the dynamics of root system growth, gas exchange, corn crop productivity, and microbial activity in the rhizospheric soil in a no-till area with different levels of available soil phosphorus. The experiment was conducted during the 2019/2020 and 2020/2021 growing seasons. At 75 days after plant emergence, root morphological parameters (total root length (cm), average root diameter (mm), root surface area (cm2), and root volume), shoot biomass production, P content in the plant shoots, gas exchange, and microbiological attributes of the rhizospheric soil of corn were evaluated. At the end of the cycle, corn grain yield was determined. A beneficial effect of AMF inoculation was observed on the root and shoot parameters regardless of soil P level. Under conditions of evenly distributed rainfall during the experiment (2019/2020 season), AMF inoculation contributed to a 90% increase in acid phosphatase activity and a 76% increase in microbial biomass carbon (C-BIO), independent of soil P level. In contrast, under water deficit conditions (2020/2021 season), AMF inoculation provided a 29% increase in grain yield. We concluded that introducing a commercial mycorrhizal inoculant in corn benefits root system morphological parameters and physiological traits, and favors the activity of enzymes related to increased P availability, contributing to increased crop productivity in a no-till system.

Animal manure can be used as a source of nutrients in cropping systems throughout the world. However, in subtropical climates, the impacts of animal manure application over multiple years on crop productivity and on the total organic carbon (TOC) and total nitrogen (TN) stocks in the soil profile are not well understood. In this study, we aimed to evaluate how animal manure application carried out over more than 17 years can impact corn productivity and TOC and TN stocks in different soil layers. This long-term study was conducted from 2004 to 2021 under no-till conditions in southern Brazil. The treatments included pig slurry (PS), cattle slurry (CS), pig deep litter (PDL), mineral fertilizer (NPK) and a control (no fertilizer application). To determine soil TOC and TN stocks, soil samples were collected from the 0.00-0.10, 0.10-0.20, 0.20-0.30, 0.30-0.40 and 0.40-0.50 m layers in December 2008, 2012, 2016 and 2020. Corn productivity was evaluated for the 2008/09, 2012/13, 2016/17, and 2020/21 crops. The highest yields and TOC and TN stocks were observed in soils with pig deep litter and cattle slurry application. In the sandy soil under a no-till system after 26 animal manure applications over 17 years, the highest TOC and TN stocks were observed in the 0.00-0.10 m layer. On average, the TOC stocks obtained for the 0.00-0.10 m layer were 11.21, 14.88, 15.82, 22.59 and 15.16 Mg ha-1 for the control, PS, CS, PDL and NPK treatments, respectively. The soil TN stocks in the 0.00-0.10 m layer were 1.06, 1.40, 1.65, 2.03 and 1.43 Mg ha-1 for the control, PS, CS, PDL and NPK treatments, respectively. The application of pig deep litter to the soil over 17 years resulted in a notable increase in TOC and TN levels, playing a crucial role in increasing the productivity of maize crops.

Assessing the phosphorus (P) balance in agricultural soils is crucial for optimizing its use and reducing contamination risks. The objective of this study was to evaluate the impact of different animal wastes on the distribution of P in soil profiles subjected to 12 years of successive applications of animal wastes and mineral phosphate fertilizer, within a crop rotation system under no-till system. The study was conducted from 2004 to 2016 in the southern region of Brazil. The treatments were the applications of pig slurry (PS), cattle slurry (CS), pig deep-litter (PD), mineral fertilizer (MF), and a control treatment without application. The highest accumulation of P and its movement was observed in the 0–40 cm layer, in the soil submitted to applications of all P sources. The inputs of P via MF, CS, PS, and PD promoted the accumulation of 18, 42, 48, and 100 kg P ha−1 year−1. The P mass balance showed that between 77 and 98% of the P added by animal manure and MF was accounted for in grain exports (17–34%), soil storage (41–72%), and post-harvest residues (<1%), with the remaining 2–33%, unaccounted for, which was attributed, especially, to P transfer at the soil surface.

Nitrogen (N) is often applied to soil surface during the grapevine cycle, increases N losses. One way to reduce N losses lies on its application method, however how N dose and application mode impact on grapevines remain poorly investigated. The aim of this study is to evaluate the root growth, as well as grape must yield and composition, in a sandy soil and subjected to different N application doses and modes under subtropical climate conditions. Grapevines were implanted in 2011 and, since 2014, they were subjected to surface (N-Surf), and fertigation (N-Fert) N application, at rates of 0, 40 and 100 kg N ha−1 year−1. Leaf N concentration, yield, must quality parameters and root system morphology were evaluated in the 2016/2017 and 2017/2018 seasons. The application of N in both rates (40 and 100 kg N ha−1 year−1), in the N-Surf and N-Fert methods, increased the surface area of root, number of living roots and root production. The application of N rates, in both N application modes, provided adequate N supply to the soil and increased root system development, which contributed to the increase of soil N uptake by plants, higher N concentration in leaves and greater grape yield. However, N supply decreased the quality of the must, as observed in decreased TSS and total anthocyanins values and in increased total titratable acidity values, which are not desirable for red wine making processes.

Organic wastes, fertilizers, organominerals, and minerals contain nutrients essential to crops and contribute to increase productivity. However their use can also lead to the accumulation of copper and zinc, which changes the distribution of their fractions and enhances the risk of toxicity to plants and the environment, thereby working against the sustainable development goals. However, the effect of manure applications on clayey soils and the effects of increasing Cu and Zn contents over the years on crop productivity remain unknown. This study aimed to evaluate the distribution and the potential for contamination of heavy metals in clayey soil with a history of the application of different types and amounts of fertilizers under Cynodon spp. grazing and no-tillage system for soybeans. In Experiment 1, Cynodon spp. were cultivated for hay production and submitted to applications of the following treatments: 0, 200, and 400 kg ha(-1) of total-N in the form of pig slurry and urea. In experiment 2, the soybean was grown and subjected to the following treatments: control, pig slurry, commercial granulated solid organic fertilizer, organomineral fertilizer blended with granules, and mineral fertilizer blended with granules. The dose of each nutrient source was determined based on the soil analysis and the recommendations of the liming and fertilization manual. The experiments were conducted for four agricultural crops where soil samples were collected in the layer of 0.00-0.10 m layer and submitted to chemical fractionation of Cu and Zn. The use of pig manure increased the availability of Cu and Zn in the soil, causing an increase in the distribution of copper organic (40.73% and 57.64% for PS200 and PS400 treatments, respectively, in Experiment 1; 67.33% for PS treatment, in Experiment 2) and residual fractions (10.01% and 7.60% for PS200 and PS400 treatments, respectively, in Experiment 1; 9.80% for PS treatment, in Experiment 2), while zinc was predominant in clay-mineral (61.04% and 92.01% for PS200 and PS400 treatments, respectively, in experiment 1; 278.90% for PS treatment, in Experiment 2) and residual fractions (2.36% for PS200 treatment in experiment 1; 9.90% for PS treatment, in Experiment 2). Additionally, the use of swine manure increased the Cu and Zn contents in the exchangeable fraction, which may potentiate the toxicity to plants and increase the potential for contamination of subsoil water. However, the increased bioavailability of Cu and Zn did not caused a loss of crop productivity but instead increased dry mass production and crop yield.

The use of organic wastes in southern Brazil is a common practice in the farms and in many of these, the criterion for defining the doses of organic wastes is to meet the N demand by crops. This may mean the accumulation of chemical elements in the soil, especially in soils managed under no-tillage systems, and enhance the transfer of these elements by surface runoff. The aim was evaluated how successive applications of organic and mineral sources of nutrients in a long-term experiment, managed under no-tillage system in a subtropical environment, influence the transfer of quantities and forms of N and P by surface runoff. The experiment was carried out in southern Brazil, in a Typic Hapludalf soil. The treatments consisted of the application of pig slurry, pig deep litter, cattle slurry, mineral fertilizer and a control, without nutrients. The doses of organic wastes were to meet the N demand by crops. Were evaluated the surface runoff and the transfers of mineral N and forms of P (soluble, particulate, and total) from 2009 to 2013 period. The amount of solution transferred by surface runoff decreased with fertilization and present a negative relationship with the soil organic matter (SOM). The transfers of mineral N increased with the increase in the contents of SOM, but decreased with the runoff. The transfers of P forms present a great relationship with the amounts of P applied and the contents of soil P extracted by Mehlich-1, and more than 55% of total P transferred by surface runoff, in the treatments that received nutrients application, is on soluble form. In addition, the transfer of soluble, particulate and total P was lower with mineral fertilizer application, when compared with organic wastes. This suggest that the use of N demand by crops as a criterium to meet the doses of organic wastes is not adequate in subtropical environment.

Injection of pig slurry (PS) into soils under no-tillage system (NTS) is more efficient for improving soil chemical and physical attributes, and reducing C and N emissions, than surface applications. This study evaluated the effect of using injection and surface application of PS, compared to NPK and control treatments, on the soil aggregate, C and N contents, and isotopes C-13 and N-15. The NTS consisted of rotations of summer (maize) and winter (black oat and wheat) grasses from 2011 to 2015. The treatments were PS injected into the soil (PSI), PS applied on the soil surface (PSS), chemical fertilization (NPK), and control (CTRL). The following soil properties were evaluated in the 0-5, 5-10, and 10-20 cm layers: aggregate stability (geometric mean diameter - GMD; aggregate mass distribution); total organic carbon (TOC) and total nitrogen (TN) in macroaggregates (8.0-0.25 mm), microaggregates (<0.25 mm), and bulk soil (<2.0 mm); and isotopes C-13 and N-15 in macro and microaggregates. The application of PSI improved the soil physical attributes, presenting higher GMD (0-5 cm) than the PSS, NPK, and CTRL treatments. In the 5-10 cm layer, the PSI treatments were more efficient in increasing the GMD and macroaggregate mass than the NPK. PSI also was more efficient in increasing TOC and TN when compared to PSS, and generated a higher GMD, which are protectors of these elements in the soil. The natural abundance of N-15 denoted the lower soil organic matter decomposition in the PSI treatment when compared to the PSS. The natural abundance of C-13 showed less-negative values in macroaggregates than in microaggregates, denoting that the soil management practices and crops used (grasses) affected positively the abundance of C-13. After seven applications of PS in maize-oat-wheat rotation in NTS, the application of PSI was more efficient in improving the soil physical and chemical attributes than the application of PSS.

The injection of pig slurry in the soil, associated with the no-tillage system and the reduction of carbon and nitrogen losses through volatilisation, can positively influence the carbon and nitrogen contents in the soil organic matter (SOM) fractions. The objective of the present study was to evaluate the effect of surface and injected applications of pig slurry to soils under a no-tillage system on soil organic carbon (SOC) and soil total nitrogen (STN) contents in particle-size fractions of the SOM. The no-tillage system included a crop rotation with grass species, summer maize, and winter black oat and wheat grown from 2011 to 2015. The treatments consisted of injected application of pig slurry, surface applications of pig slurry, application of chemical fertiliser (NPK), and a control with no soil fertiliser application. The 0–5, 5–10, and 10–20 cm soil layers were evaluated for SOC and STN contents, and for particle-size fractions: particulate organic carbon, particulate organic nitrogen, mineral-associated organic carbon, and mineral-associated organic nitrogen. We also evaluated the carbon and nitrogen contents and mass in the light organic matter. The injection of pig slurry increased carbon and nitrogen contents of all SOM fractions compared to surface application of pig slurry. These results suggest that the use of injected pig slurry to the soil under crop rotation in no-tillage reduces carbon and nitrogen losses by volatilisation and emissions to the atmosphere. We recommend the application of pig slurry by injecting in soil because it promotes higher increases in the SOM fractions. This form of application of pig slurry to the soil was shown as an effective and environmentally sustainable method for the conservation and improvement of soil quality.

Soil erosion in Brazil is very high, and there is need to promote aggregate stability technics to increase the soil organic matter and the soil water infiltration, with a consequent decrease in erosion processes. Applications of animal manure on sandy loam soil may increase carbon (C) and nitrogen (N) contents in soil aggregates, causing increased aggregate stability. This study aimed to evaluate the contents of total organic carbon (TOC) and total nitrogen (TN) as well as the physical properties of a sandy loam soil subjected to 11 years of application animal manure and mineral fertilizer. The experiment was conducted under no-tillage (NT) system with corn (Zea mays L.)/black oat (Avena strigose Schreb.), bean (Phaseolus vulgaris L.)/black oat, and corn/wheat (Triticum spp.) crops. The following treatments were used: control (no fertilization), pig slurry (PS), pig deep litter (DL), cattle slurry (CS), and mineral fertilizer (NPK). Soil aggregates were obtained from undisturbed soil samples collected at soil depths of 0 to 5, 5 to 10, and 10 to 20 cm. Applications of PS, DL, and CS on soil increased TOC and TN contents, and increasing weighted mean diameter (WMD) and geometric mean diameter (GMD) in the topsoil. Use of DL and CS increased TOC at 0 to 5 cm in comparison to PS, NPK, and control. The use of animal manure also resulted in higher TN contents at 0 to 5 and 10 to 20 cm compared to control. The use of animal manure for 11 years under NT reduced the amount of mesoaggregates (2.0 > Ø ≥ 0.25 mm) and microaggregates (Ø < 0.25 mm) and increased GMD in the topsoil in comparison to the NPK and control. The animal manure promoted the dispersion of clays at 5 to 10 and 10 to 20 cm, resulting in lower soil aggregation in depth. Principal component analysis confirmed that animal manure reduced the degree of flocculation, with a consequent decrease in aggregation indexes, as it grouped the manure treatments in opposition to the NPK and control treatments.