Manure storage operations mitigate nutrient losses and their products can sustain soil fertility and enhance wheat productivity.

Livestock manure is a valuable source of nutrients for plants. However, poor handling practices during storage resulted in nutrient losses from the manure and decrement in its nitrogen (N) fertilizer value. We explored the influence of divergent storage methods on manure chemical composition, carbon (C) and N losses to the environment as well as fertilizer value of storage products after their application to the wheat. Fresh buffalo manure (FM) was subjected to different storage operations for a period of ∼6 months, (i) fermentation by covering with a plastic sheet (CM) (ii) placed under the roof (RM) (iii) heap was unturned (SM) to remain stacked at an open space and (iv) manure heap turned monthly (TM) to make compost. During storage, 8, 24, 45 and 46% of the initial Ntotal was lost from CM, RM, SM, and TM, respectively. The respective C losses from these treatments were 16, 34, 47 and 44% of the initial C content. After stored manures application to the wheat crop, mineral N in the soil remained 27% higher in CM (14.1 vs. 11.1 kg ha-1) and 3% (10.8 vs. 11.1 kg ha-1) lower in SM compared to FM treatment. In contrast, microbial biomass C and N was 35 (509 vs.782 mg C kg-1 soil) and 25% (278 vs.370 mg N kg-1 soil) lower in CM than FM treatment, respectively indicating lower N immobilization of CM in the soil. These findings could result in the highest grain yield (5166 kg ha-1) and N uptake (117 kg ha-1) in CM and the lowest in SM treatments (3105 and 61 kg ha-1, respectively). Similarly, wheat crop recovered 44, 15 and 13% N from CM, TM and SM, respectively. Hence, management operations play a critical role in conserving N during storage phase and after stored manure application to the field. Among the studied operations, storing animal manure under an impermeable plastic sheet is a much better and cheaper option for decreasing N losses during storage and improving wheat yield when incorporated into the soil. Therefore, by adopting this manure storage technique, farmers can improve the agro-environmental value of animal manure in Pakistan.

Bedding additives reduce ammonia emission and improve crop N uptake after soil application of solid cattle manure.

This study examined the influences of three potential additives, i.e., lava meal, sandy soil top-layer and zeolite (used in animal bedding) amended solid cattle manures on (i) ammonia (NH3), dinitrous oxide (N2O), carbon dioxide (CO2) and methane (CH4) emissions and (ii) maize crop or grassland apparent N recovery (ANR). Diffusion samplers were installed at 20 cm height on grassland surface to measure the concentrations of NH3 from the manures. A photoacoustic gas monitor was used to quantitate the fluxes of N2O, CH4 and CO2 after manures' incorporation into the maize-field. Herbage ANR was calculated from dry matter yield and N uptake of three successive harvests, while maize crop ANR was determined at cusp of juvenile stage, outset of grain filling as well as physiological maturity stages. Use of additives decreased the NH3 emission rates by about two-third from the manures applied on grassland surface than control untreated-manure. Total herbage ANR was more than doubled in treated manures and was 25% from manure amended with farm soil, 26% and 28% from zeolite and lava meal, respectively compared to 11% from control manure. In maize experiment, mean N2O and CO2 emission rates were the highest from the latter treatment but these rates were not differed from zero control in case of manures amended with farm soil or zeolite. However, mean CH4 emissions was not differed among all treatments during the whole measuring period. The highest maize crop ANR was obtained at the beginning of grain filling stage (11-40%), however ample lower crop recoveries (8-14%) were achieved at the final physiological maturity stage. This phenomenon was occurred due to leaf senescence N losses from maize crop during the period of grains filling. The lowest losses were observed from control manure at this stage. Hence, all additives decreased the N losses from animal manure and enhanced crop N uptake thus improved the agro-environmental worth of animal manure.

Improvements in wheat productivity and soil quality can accomplish by co-application of biochars and chemical fertilizers.

The beneficial role of biochar is evident in most of infertile soils, however this is argued that increment in crop yield owing to biochar application does not always achieve in cultivated/fertile soils. The nutrient biochar believed to enhance crop yield and soil fertility than structural biochar that may offset the positive effect of chemical fertilizer on crop performance but improves soil structural properties. Therefore, we investigated the effect of biochars [produced from nutrient rich feedstocks like poultry manure (PMB) and farmyard manure (FMB) and structural feedstocks such as wood chips (WCB) and kitchen waste (KWB)], and chemical fertilizers (CF) when applied alone or in combination on soil chemical properties, wheat growth, yield and nitrogen uptake in a cultivated clay loam soil. Sole biochar treatments increased the total carbon and mineral nitrogen content that were 21 and 106% higher, respectively compared to control after 128days (P<0.001). Contrarily, sole biochars application did not increase wheat biological yield and N uptake compared to control (P>0.05) except PMB, the nutrient biochar (P<0.05). Compared to control, grain yield was 6 and 12% lower in WCB and FMB, respectively but not differed from KWB, PMB or WCB-CF. Conversely, co-application of biochars and CF treatments increased crop biological yield but the increment was the highest in nutrient biochars FMB or PMB (29 or 26%), than structural biochars WCB and KWB (15 and 13%), respectively (P<0.05). For N uptake, this increment varies between 16 and 27% and again nutrient biochar has significantly higher N uptake than structural biochars. Hence, nutrient biochars (i.e. PMB) benefited the soil fertility and crop productivity more than structural biochars. Therefore, for immediate crop benefits, it is recommended to use nutrient biochar alone or in combination with chemical fertilizer. Such practice will improve crop performance and the quality of cultivated soil.