616 EXPERIMENT STATION RECORD. 



potash per acre are brought on the field by the irrigation water. This is not as 

 much phosphoric acid, nitrogen, or potash as is consumed I)y a crop of rice. It 

 is estimated that the seepage and off-flow waters carry off approximately 4.5 

 lbs. phosphoric acid, 3.4 lbs. potash, and probably larger amounts of nitrogen. 

 " The net result of the irrigation waters is thiis an average gain of 3.1 lbs. 

 phosphoric acid and 20 lbs. potash per acre, and a loss of nitrogen. A loss of 

 approximately 20 lbs. nitrogen per acre by percolation during the winter may 

 take place, with small amounts of potash and phosphoric acid. 



" The soil loses, in the growth of an irrigated rice crop, on an average of 12 

 lbs. phosphoric acid, GO lbs. of nitrogen, and 22 lbs. potash per acre, if the 

 straw is removed and the stubble burned. If, however, the stubble is plowed 

 under, and the straw ashes returned to the field they come from, there is an 

 average loss of 9 lbs. phosphoric acid, 57 lbs. nitrogen, and apparently a gain 

 of 15 lbs. of potash." 



Of the soils examined those of Jefferson, Orange, De Witt, and Victoria coun- 

 ties, as well as the black soils of Brazoria, contained small quantities of phos- 

 phoric acid. Those of Harris County, the Rio Grande Valley, and the Brazos 

 bottom soils of Brazoria contained an abundance of phosphoric acid. Orange 

 County soil was low in potash, the others contained a moderate amount, while 

 the Rio Grande Valley soil was rich in this constituent. The only soil low in 

 lime was that of Orange County. 



Nitrification studies indicate that the soils of Orange and Brazoria counties 

 are too low in phosphoric acid for efficient nitrification. All the soils examined 

 contained very small amounts of chemically available phosphoric acid as meas- 

 ured by fifth-normal nitric acid. The chemically available potash determined 

 in the same way was low in the Brazoria and Orange county soils, but present 

 in moderate amounts in other soils. 



Regai'ding the treatment of rice soils, the author states that " burning the 

 straw is wasteful, but if burned, the ashes should be scattered on the field from 

 whence they came. The stubble should be plowed under if possible. The 

 nitrogen content of the soil should be maintained by growing leguminous crops 

 (cowpeas, vetch, etc.), which are plowed under witli caution, grazed off. or made 

 into hay." 



Results of analyses of cultivated soils, F. F. Villasknor (Mr»). y Rev. Soc. 

 C'leiit. ''Antonio Alzate," 23 {190.')), JSiO. 5-0, pp. 1S7-1HH: (WOO), No. 7-12, pp. 

 ,389-39.'/). — Physical and chemical analyses of ;» samples of Mexican soils are 

 talmlated. 



A note on the protective action of colloids on suspended clay and natural 

 clay soils, 10. Fickkndey and B. Tollens (Jour. Landiv., off (1906), No. .'/, pp. 

 3'/3-.}')<! ). — This article discusses the results of experiments in which 20 cc. of 

 solutions of different colloids of varying concentrations was mixed with 1 cc. 

 of kaolin suspension and twice-normal electrolytes of different kinds (potas- 

 sium hydroxid, hydrochloric acid, etc.) were added. It was found that in such 

 cases starch exerted no influence, but that tannin produced a marked effect in 

 preventing flocculation (but only in alkaline solution), while the amphoteric 

 gelatin exerted a positive influence in acid solutions and a negative influence 

 in alkaline solutions. The greatest protective action was observed with about 

 jig-normal hydrochloric acid containing from 0.1 to 0.2 gni. of gelatin per liter. 

 The beneficial effect of lime on the structure of soils is explained on the 

 basis of these results as due to the fact that lime forms insoluble compounds 

 with the humus acids and that these compounds remain insoluble in spite of the 

 alkaline reaction of the soil. It is claimed that the calcium ion is especially 

 active in flocculations and that the flocculating jwwer of igais bears a direct 

 relation to their precipitation reactions. 



