Litter decay in rangeland sites with varying history of human disturbance: a study with Hazargangi Chiltan mountain

Hazarganji Chiltan National Park in Balochistan, Pakistan was established in 1980 and the protected area was further extended in 1998. Large area of this mountain is still open for unmanaged human disturbances such as collection of wood for fuel purpose and livestock grazing. Removal of vegetation of rangelands has a significant negative impact on soil organic matter(SOM). This research evaluates litter decomposition in three sites of Hazarganji Chiltan mountain with varying history of human disturbances(unprotected site, young protected site and old protected site). Twigs of Pistacia khinjuk with approximately equal weight and length were placed in litter bags of mesh size 2 mm and were buried in 0-5 cm depth in three sites in January. Half of the twigs of each site received rain simulation in April, August, October, November and January while the other half of the twigs were subjected under natural conditions for 15 months. Twigs from each plot of each treatment of each site were collected from soil after every rain simulation in the previous month of experiment and were processed for weight loss assessment. Results showed that weight loss of twigs by decomposition was significantly higher in the soil of unprotected site as compared to other two sites and there was no difference between rain simulation and control treatments except that loss of weight of twigs of unprotected site was higher under control than rain simulation condition. To confirm that SOM was the major controlling factor for the decomposition of litter decay, soils of each site were collected and burned to remove SOM;thereafter, burned soil samples were mixed with homogenous powder of oven-dried native plants, incubated for 6 months and were provided with dissolved organic matter of the soils of each site. Results showed that there was no difference in the decomposition of litter between soils under controlled laboratory condition, which confirmed that SOM was a major controlling factor for the litter decay in soil under field conditions. The pyrosequencing analysis of the DNA of soils collected from three sites revealed the presence of bacterial species Thermovum composti.

Poultry Manure as an Organic Fertilizer with or without Biochar Amendment:Influence on Growth and Heavy Metal Accumulation in Lettuce and Spinach and Soil Nutrients

This pot-based study investigated the influence of poultry manure and 1:1 mixture of poultry manure+biochar(produced from farmyard manure[FYM]or wood),on the biomass production and concentration of heavy metals in leaves of lettuce and spinach.The concentration of mineral nitrogen(N)and soluble inorganic phosphorus(P)of soils cultivated with these vegetables was also investigated.The application of poultry manure or FYM biochar in soil as 10%(equivalent to 60 t ha^(-1),an estimated 1726.8 kg ha^(-1)N in poultry manure and 1353.9 kg ha^(-1)N in FYM)and 15%amendment(equivalent to 90 t ha^(-1),an estimated 2590.2 kg ha^(-1)N in poultry manure and 2030.8 kg ha^(-1)N in FYM)significantly decreased biomass production of lettuce as compared to control(no fertilizer added)treatment.However,mixture of poultry manure with wood-derived biochar at both application rates(i.e.,10%and 15%)and with FYM biochar at lower application rate(i.e.,10%)caused 2-3-fold increase in aboveground plant biomass and 2-14-fold increase in root biomass(p<0.05).Furthermore,as compared to control treatment,a significant~2-3-fold increase in aboveground plant biomass was also observed in response to mixture of poultry manure with wood-derived and FYM derived biochars at 10%amendment rates.As compared to control treatment,concentration of mineral N and soluble inorganic P were higher in soils of all other treatments.In spinach,amendment of poultry manure or its co-amendment with biochar of FYM significantly increased aboveground plant biomass at 7%(equivalent to 42 t ha^(-1))as compared to 3%and 5%amendment rates(equivalent to 18 and 30 t ha^(-1)respectively).The concentration of soil mineral N and soil soluble mineral P was not different between treatments.In lettuce,wood-derived biochar did not reduce concentration of heavy metals(i.e.,manganese(Mn),copper(Cu),iron,(Fe),cadmium(Cd),lead(Pb),nickel(Ni)and cobalt(Co)than FYM-derived biochar while in spinach,as compared to poultry manure,co-amendment of poultry manure with wood-derived biochar reduced concentration of heavy metals,indicating differential responses of crops to organic amendments.